Revert "Detect broken setlocale on musl"

This reverts commit 2e66c35.

Author: nikic

ext/standard/config.m4

@@ -368,24 +368,6 @@ if test "$ac_cv_strptime_decl_fails" = "yes"; then
   AC_DEFINE([HAVE_STRPTIME_DECL_FAILS], 1, [whether strptime() declaration fails])
 fi
 
-dnl musl has a badly broken setlocale() implementation that always reports success.
-AC_CACHE_CHECK([whether setlocale() is broken], ac_cv_setlocale_broken, [
-AC_RUN_IFELSE([AC_LANG_SOURCE([[
-#include <locale.h>
-int main() {
-    return setlocale(LC_CTYPE, "This locale certainly does not exist") == NULL;
-}
-]])],[
-  ac_cv_setlocale_broken=yes
-],[
-  ac_cv_setlocale_broken=no
-],[
-  ac_cv_setlocale_broken=no
-])])
-if test "$ac_cv_setlocale_broken" = "yes"; then
-  AC_DEFINE([HAVE_BROKEN_SETLOCALE], 1, [whether setlocale() is broken])
-fi
-
 dnl
 dnl Check for arc4random on BSD systems
 dnl

ext/standard/string.c

@@ -4662,15 +4662,6 @@ PHP_FUNCTION(setlocale)
 
 # ifndef PHP_WIN32
 		retval = php_my_setlocale(cat, loc ? ZSTR_VAL(loc) : NULL);
-#  if HAVE_BROKEN_SETLOCALE
-		/* musl libc always reports success for setlocale().
-		 * Manually whitelist the allowed locales "", "C" and "C.UTF-8" instead. */
-		if (retval && loc && ZSTR_LEN(loc) != 0
-				&& !zend_string_equals_literal(loc, "C")
-				&& !zend_string_equals_literal(loc, "C.UTF-8")) {
-			retval = NULL;
-		}
-#  endif
 # else
 		if (loc) {
 			/* BC: don't try /^[a-z]{2}_[A-Z]{2}($|\..*)/ except for /^u[ks]_U[KS]$/ */