Revert "Suppress duplicated-branches compiler warning in libmagic"

This reverts commit c16163c.

Author: Girgias

ext/fileinfo/config.m4

@@ -49,7 +49,7 @@ int main(void)
     libmagic_sources="$libmagic_sources libmagic/strcasestr.c"
   ],[AC_MSG_RESULT([skipped, cross-compiling])])
 
-  PHP_NEW_EXTENSION(fileinfo, fileinfo.c $libmagic_sources, $ext_shared,,"-I@ext_srcdir@/libmagic -Wno-duplicated-branches")
+  PHP_NEW_EXTENSION(fileinfo, fileinfo.c $libmagic_sources, $ext_shared,,-I@ext_srcdir@/libmagic)
   PHP_ADD_BUILD_DIR($ext_builddir/libmagic)
 
   AC_CHECK_FUNCS([utimes strndup])