don't set EXTENSION_DIR by default

Author: henderkes

config/env.ini

@@ -50,7 +50,7 @@ SPC_SKIP_DOCTOR_CHECK_ITEMS=""
 ; RHEL: /usr/lib64/php/modules
 ; Alpine: /usr/lib/php{PHP_VERSION}/modules
 ; where {PHP_VERSION} is 84 for php 8.4
-EXTENSION_DIR=
+; EXTENSION_DIR=
 
 [windows]
 ; php-sdk-binary-tools path