move __strftime_fmt_1 declaration to time_impl.h

this is a helper function from strftime that's also used by wcsftime.

src/time/time_impl.h

@@ -8,3 +8,4 @@ const char *__tm_to_tzname(const struct tm *);
 int __secs_to_tm(long long, struct tm *);
 void __secs_to_zone(long long, int, int *, long *, long *, const char **);
 const unsigned char *__map_file(const char *, size_t *);
+const char *__strftime_fmt_1(char (*)[100], size_t *, int, const struct tm *, locale_t, int);

src/time/wcsftime.c

@@ -2,10 +2,9 @@
 #include <time.h>
 #include <locale.h>
 #include "locale_impl.h"
+#include "time_impl.h"
 #include "libc.h"
 
-const char *__strftime_fmt_1(char (*s)[100], size_t *l, int f, const struct tm *tm, locale_t loc, int pad);
-
 size_t __wcsftime_l(wchar_t *restrict s, size_t n, const wchar_t *restrict f, const struct tm *restrict tm, locale_t loc)
 {
 	size_t l, k;