maint: avoid warnings via patched versions of gnulib's regex functions

* gl/lib/regcomp.c.diff: New file.
* gl/lib/regex_internal.c.diff: Likewise.
* gl/lib/regex_internal.h.diff: Likewise.
* gl/lib/regexec.c.diff: Likewise.

gl/lib/regcomp.c.diff

@@ -0,0 +1,82 @@
+diff --git c/lib/regcomp.c i/lib/regcomp.c
+index 6472ff6..665b2ab 100644
+--- c/lib/regcomp.c
++++ i/lib/regcomp.c
+@@ -18,6 +18,8 @@
+    with this program; if not, write to the Free Software Foundation,
+    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+
++#include "intprops.h"
++#include "verify.h"
+ static reg_errcode_t re_compile_internal (regex_t *preg, const char * pattern,
+ 					  size_t length, reg_syntax_t syntax);
+ static void re_compile_fastmap_iter (regex_t *bufp,
+@@ -541,7 +543,7 @@ regerror (errcode, preg, errbuf, errbuf_size)
+     size_t errbuf_size;
+ #else /* size_t might promote */
+ size_t
+-regerror (int errcode, const regex_t *_Restrict_ preg,
++regerror (int errcode, const regex_t *_Restrict_ preg _UNUSED_PARAMETER_,
+ 	  char *_Restrict_ errbuf, size_t errbuf_size)
+ #endif
+ {
+@@ -1375,7 +1377,7 @@ calc_first (void *extra, bin_tree_t *node)
+
+ /* Pass 2: compute NEXT on the tree.  Preorder visit.  */
+ static reg_errcode_t
+-calc_next (void *extra, bin_tree_t *node)
++calc_next (void *extra _UNUSED_PARAMETER_, bin_tree_t *node)
+ {
+   switch (node->token.type)
+     {
+@@ -2571,7 +2573,8 @@ parse_dup_op (bin_tree_t *elem, re_string_t *regexp, re_dfa_t *dfa,
+   /* This loop is actually executed only when end != REG_MISSING,
+      to rewrite <re>{0,n} as (<re>(<re>...<re>?)?)?...  We have
+      already created the start+1-th copy.  */
+-  if ((Idx) -1 < 0 || end != REG_MISSING)
++  verify (! TYPE_SIGNED (Idx));
++  if (end != REG_MISSING)
+     for (i = start + 2; i <= end; ++i)
+       {
+ 	elem = duplicate_tree (elem, dfa);
+@@ -2731,7 +2734,8 @@ static reg_errcode_t
+ internal_function
+ build_collating_symbol (bitset_t sbcset,
+ # ifdef RE_ENABLE_I18N
+-			re_charset_t *mbcset, Idx *coll_sym_alloc,
++			re_charset_t *mbcset _UNUSED_PARAMETER_,
++			Idx *coll_sym_alloc _UNUSED_PARAMETER_,
+ # endif
+ 			const unsigned char *name)
+ {
+@@ -3309,7 +3313,8 @@ parse_bracket_exp (re_string_t *regexp, re_dfa_t *dfa, re_token_t *token,
+
+ static reg_errcode_t
+ parse_bracket_element (bracket_elem_t *elem, re_string_t *regexp,
+-		       re_token_t *token, int token_len, re_dfa_t *dfa,
++		       re_token_t *token, int token_len,
++		       re_dfa_t *dfa _UNUSED_PARAMETER_,
+ 		       reg_syntax_t syntax, bool accept_hyphen)
+ {
+ #ifdef RE_ENABLE_I18N
+@@ -3396,8 +3401,9 @@ parse_bracket_symbol (bracket_elem_t *elem, re_string_t *regexp,
+
+ static reg_errcode_t
+ #ifdef RE_ENABLE_I18N
+-build_equiv_class (bitset_t sbcset, re_charset_t *mbcset,
+-		   Idx *equiv_class_alloc, const unsigned char *name)
++build_equiv_class (bitset_t sbcset, re_charset_t *mbcset _UNUSED_PARAMETER_,
++		   Idx *equiv_class_alloc _UNUSED_PARAMETER_,
++		   const unsigned char *name)
+ #else /* not RE_ENABLE_I18N */
+ build_equiv_class (bitset_t sbcset, const unsigned char *name)
+ #endif /* not RE_ENABLE_I18N */
+@@ -3798,7 +3804,7 @@ free_token (re_token_t *node)
+    and its children. */
+
+ static reg_errcode_t
+-free_tree (void *extra, bin_tree_t *node)
++free_tree (void *extra _UNUSED_PARAMETER_, bin_tree_t *node)
+ {
+   free_token (&node->token);
+   return REG_NOERROR;

gl/lib/regex_internal.c.diff

@@ -0,0 +1,25 @@
+diff --git a/lib/regex_internal.c b/lib/regex_internal.c
+index 904b88e..61c8d9d 100644
+--- a/lib/regex_internal.c
++++ b/lib/regex_internal.c
+@@ -18,6 +18,8 @@
+    with this program; if not, write to the Free Software Foundation,
+    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+
++#include "verify.h"
++#include "intprops.h"
+ static void re_string_construct_common (const char *str, Idx len,
+ 					re_string_t *pstr,
+ 					RE_TRANSLATE_TYPE trans, bool icase,
+@@ -1390,7 +1392,10 @@ static void
+ internal_function
+ re_node_set_remove_at (re_node_set *set, Idx idx)
+ {
+-  if (idx < 0 || idx >= set->nelem)
++  verify (! TYPE_SIGNED (Idx));
++  /* if (idx < 0)
++     return; */
++  if (idx >= set->nelem)
+     return;
+   --set->nelem;
+   for (; idx < set->nelem; idx++)

gl/lib/regex_internal.h.diff

@@ -0,0 +1,14 @@
+diff --git i/lib/regex_internal.h w/lib/regex_internal.h
+index 859832f..3c7fe06 100644
+--- i/lib/regex_internal.h
++++ w/lib/regex_internal.h
+@@ -826,7 +826,8 @@ re_string_wchar_at (const re_string_t *pstr, Idx idx)
+
+ static int
+ internal_function __attribute ((pure))
+-re_string_elem_size_at (const re_string_t *pstr, Idx idx)
++re_string_elem_size_at (const re_string_t *pstr _UNUSED_PARAMETER_,
++			Idx idx _UNUSED_PARAMETER_)
+ {
+ # ifdef _LIBC
+   const unsigned char *p, *extra;

gl/lib/regexec.c.diff

@@ -0,0 +1,45 @@
+diff --git a/lib/regexec.c b/lib/regexec.c
+index 21a8166..7762437 100644
+--- a/lib/regexec.c
++++ b/lib/regexec.c
+@@ -18,6 +18,8 @@
+    with this program; if not, write to the Free Software Foundation,
+    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+
++#include "verify.h"
++#include "intprops.h"
+ static reg_errcode_t match_ctx_init (re_match_context_t *cache, int eflags,
+ 				     Idx n) internal_function;
+ static void match_ctx_clean (re_match_context_t *mctx) internal_function;
+@@ -378,8 +380,11 @@ re_search_2_stub (struct re_pattern_buffer *bufp,
+   Idx len = length1 + length2;
+   char *s = NULL;
+
+-  if (BE (length1 < 0 || length2 < 0 || stop < 0 || len < length1, 0))
+-    return -2;
++  verify (! TYPE_SIGNED (Idx));
++  if (BE (len < length1, 0))
++     return -2;
++  /* if (BE (length1 < 0 || length2 < 0 || stop < 0, 0))
++     return -2; */
+
+   /* Concatenate the strings.  */
+   if (length2 > 0)
+@@ -431,11 +436,14 @@ re_search_stub (struct re_pattern_buffer *bufp,
+   Idx last_start = start + range;
+
+   /* Check for out-of-range.  */
+-  if (BE (start < 0 || start > length, 0))
+-    return -1;
++  verify (! TYPE_SIGNED (Idx));
++  /* if (BE (start < 0, 0))
++     return -1; */
++  if (BE (start > length, 0))
++     return -1;
+   if (BE (length < last_start || (0 <= range && last_start < start), 0))
+     last_start = length;
+-  else if (BE (last_start < 0 || (range < 0 && start <= last_start), 0))
++  else if (BE (/* last_start < 0 || */ (range < 0 && start <= last_start), 0))
+     last_start = 0;
+
+   __libc_lock_lock (dfa->lock);