ext/gettext/{config.m4,gettext.c}: don't assume secure_getenv exists

This is killing the Windows and macOS builds. We now check for
secure_getenv() in ./configure and fall back to the regular getenv()
if it is not available. This should not actually matter in the one
case we need it, namely on musl, because musl provides secure_getenv().

Author: orlitzky

ext/gettext/config.m4

@@ -11,6 +11,9 @@ if test "$PHP_GETTEXT" != "no"; then
   AS_VAR_IF([GETTEXT_DIR],,
     [AC_MSG_ERROR([Cannot locate header file libintl.h])])
 
+  dnl POSIX 2024, but missing on Windows and macOS at least
+  AC_CHECK_FUNCS([secure_getenv])
+
   GETTEXT_LIBDIR=$GETTEXT_DIR/$PHP_LIBDIR
   GETTEXT_INCDIR=$GETTEXT_DIR/include
 

ext/gettext/gettext.c

@@ -202,12 +202,16 @@ PHP_FUNCTION(bindtextdomain)
 			 * provide one (or more) via the MUSL_LOCPATH
 			 * environment variable. For lack of a better
 			 * idea, we return MUSL_LOCPATH if it is set,
-			 * even though it may contain multiple paths.
-			 * We use secure_getenv() because the musl docs
+			 * even though it may contain multiple paths. */
+#if HAVE_SECURE_GETENV
+			/* We prefer secure_getenv() because the musl docs
 			 * say that MUSL_LOCPATH will be ignored in the
 			 * scenarios where secure_getenv() will return
 			 * NULL rather than the value of the variable. */
 			musl_locpath = secure_getenv("MUSL_LOCPATH");
+#else
+			musl_locpath = getenv("MUSL_LOCPATH");
+#endif
 			if (musl_locpath == NULL) {
 				RETURN_FALSE;
 			}