use a more consistent quoting style.

See <http://lists.gnu.org/archive/html/bug-bison/2012-01/msg00120.html>.
Use quotearg as often as possible instead of leaving the choice of
the quotes to the translators.  Use shorter messages.  Factor similar
messages to a single format, to make localization easier.

	* src/files.c, src/getargs.c, src/muscle-tab.c, src/reader.c
	* src/scan-code.l, src/scan-gram.l, src/symtab.c:
	Use quote() or quotearg_colon() on printf arguments instead of
	quotes in the format string.
	* data/bison.m4: Keep sync with the changes in muscle-tab.c.

	* tests/skeletons.at, tests/input.at, tests/regression.at: Adjust
	expected messages.
(cherry picked from commit 4a9cd8f24a)

Conflicts:

	src/muscle-tab.c

src/files.c

@@ -25,6 +25,7 @@
 #include <dirname.h>
 #include <get-errno.h>
 #include <quote.h>
+#include <quotearg.h>
 #include <stdio-safer.h>
 #include <xstrndup.h>
 
@@ -109,7 +110,8 @@ xfopen (const char *name, const char *mode)
 
   ptr = fopen_safer (name, mode);
   if (!ptr)
-    error (EXIT_FAILURE, get_errno (), _("cannot open file '%s'"), name);
+    error (EXIT_FAILURE, get_errno (),
+           _("%s: cannot open"), quotearg_colon (name));
 
   return ptr;
 }