maint/sc: enable the po check

* cfg.mk (local-checks-to-skip): Add sc_po_check.
* po/POTFILES.in: Update.

cfg.mk

@@ -35,7 +35,6 @@ local-checks-to-skip =		\
   sc_error_message_period	\
   sc_error_message_uppercase	\
   sc_m4_quote_check		\
-  sc_po_check			\
   sc_program_name		\
   sc_prohibit_HAVE_MBRTOWC	\
   sc_require_config_h		\

po/POTFILES.in

@@ -19,10 +19,11 @@ lib/c-stack.c
 lib/error.c
 lib/file-type.c
 lib/getopt.c
-lib/regex.c
-lib/xmalloc.c
+lib/quotearg.c
+lib/regcomp.c
+lib/xalloc-die.c
+lib/xstrtol-error.c
 lib/version-etc.c
-lib/xmalloc.c
 
 src/analyze.c
 src/cmp.c