ctype.h: Fix unused variable warnings

If __HAVE_LOCALE_INFO__ is not defined, then the locale in the
locale-specific ctype functions is ignored.  In the previous
implementation this resulted in compiler warnings.  For example:

int main()
{
  locale_t locale;
  locale = duplocale(uselocale((locale_t)0));
  isspace_l('x', locale);
  return 0;
}

gcc -Wall main.c
main.c: In function 'main':
main.c:6:11: warning: variable 'locale' set but not used [-Wunused-but-set-variable]
    6 |  locale_t locale;
      |           ^~~~~~

1 files changed, 9 insertions, 4 deletions

diff --git a/newlib/libc/include/ctype.h b/newlib/libc/include/ctype.h
index a0009af17..8b1013ac0 100644
--- a/newlib/libc/include/ctype.h
+++ b/newlib/libc/include/ctype.h
@@ -66,6 +66,9 @@ extern int toascii_l (int __c, locale_t __l);
 #define _X	0100
 #define	_B	0200
 
+/* For C++ backward-compatibility only.  */
+extern	__IMPORT const char	_ctype_[];
+
 #ifdef __HAVE_LOCALE_INFO__
 const char *__locale_ctype_ptr (void);
 #else
@@ -108,7 +111,12 @@ const char *__locale_ctype_ptr (void);
 #ifdef __HAVE_LOCALE_INFO__
 const char *__locale_ctype_ptr_l (locale_t);
 #else
-#define __locale_ctype_ptr_l(l)	_ctype_
+static __inline char *
+__locale_ctype_ptr_l(locale_t _l)
+{
+	(void)_l;
+	return __locale_ctype_ptr();
+}
 #endif
 #define __ctype_lookup_l(__c,__l) ((__locale_ctype_ptr_l(__l)+sizeof(""[__c]))[(int)(__c)])
 
@@ -170,9 +178,6 @@ const char *__locale_ctype_ptr_l (locale_t);
 
 #endif /* !__cplusplus */
 
-/* For C++ backward-compatibility only.  */
-extern	__IMPORT const char	_ctype_[];
-
 _END_STD_C
 
 #endif /* _CTYPE_H_ */