- Only run startup() if ZEND_EXTENSIONS is defined to 1.

This fixes a link error on platforms which don't support libdl

Zend/zend_extensions.c

@@ -141,11 +141,13 @@ static void zend_extension_shutdown(zend_extension *extension)
 
 static void zend_extension_startup(zend_extension *extension)
 {
+#if ZEND_EXTENSIONS_SUPPORT
 	if (extension->startup) {
 		if (extension->startup(extension)!=SUCCESS) {
 			DL_UNLOAD(extension->handle);
 		}
 	}
+#endif
 }