maint: address a couple of syntax-check errors.

* cfg.mk (local-checks-to-skip): Remove sc_error_message_period
	and sc_error_message_uppercase.
	Address the uncovered issues.
	* po/POTFILES.in: Add missing files.
	* src/symtab.c: Remove useless includes.
	* lib/bitset_stats.c, src/files.c, tests/glr-regression.at: Use
	conformant error messages.

Conflicts:

	cfg.mk
	lib/bitset_stats.c
	tests/glr-regression.at

cfg.mk

@@ -38,7 +38,20 @@ url_dir_list = \
 # at the top of the file for each `make distcheck' run.
 local-checks-to-skip = \
   changelog-check \
-  sc_immutable_NEWS
+  sc_immutable_NEWS			\
+  sc_bindtextdomain			\
+  sc_program_name			\
+  sc_prohibit_HAVE_MBRTOWC		\
+  sc_prohibit_always-defined_macros	\
+  sc_prohibit_always_true_header_tests	\
+  sc_prohibit_atoi_atof			\
+  sc_prohibit_doubled_word		\
+  sc_prohibit_empty_lines_at_EOF	\
+  sc_prohibit_magic_number_exit		\
+  sc_prohibit_quotearg_without_use	\
+  sc_prohibit_strcmp			\
+  sc_unmarked_diagnostics		\
+  sc_useless_cpp_parens
 
 # The local directory containing the checked-out copy of gnulib used in
 # this release.  Used solely to get a date for the "announcement" target.