* bootstrap: Update from latest gnulib version

bootstrap

@@ -1,6 +1,6 @@
 #! /bin/sh
 # Print a version string.
-scriptversion=2018-07-01.02; # UTC
+scriptversion=2019-01-04.17; # UTC
 
 # Bootstrap this package from checked-out sources.
 
@@ -142,6 +142,9 @@ die() { warn_ "$@"; exit 1; }
 
 # Configuration.
 
+# Name of the Makefile.am
+gnulib_mk=gnulib.mk
+
 # List of gnulib modules needed.
 gnulib_modules=
 
@@ -970,6 +973,16 @@ fi
 bootstrap_post_import_hook \
   || die "bootstrap_post_import_hook failed"
 
+# Don't proceed if there are uninitialized submodules.  In particular,
+# the next step will remove dangling links, which might be links into
+# uninitialized submodules.
+#
+# Uninitialized submodules are listed with an initial dash.
+if $use_git && git submodule | grep '^-' >/dev/null; then
+  die "some git submodules are not initialized. "     \
+      "Run 'git submodule init' and bootstrap again."
+fi
+
 # Remove any dangling symlink matching "*.m4" or "*.[ch]" in some
 # gnulib-populated directories.  Such .m4 files would cause aclocal to fail.
 # The following requires GNU find 4.2.3 or newer.  Considering the usual