we need extensions to explicitly tell which c std they need

src/SPC/builder/Extension.php

@@ -576,7 +576,7 @@ class Extension
 
     protected function getExtraEnv(): array
     {
-        return ['CFLAGS' => '-std=c17'];
+        return ['CFLAGS' => ''];
     }
 
     /**

src/SPC/builder/extension/mongodb.php

@@ -24,4 +24,9 @@ class mongodb extends Extension
         $arg .= $this->builder->getLib('zlib') ? ' --with-mongodb-zlib=yes ' : ' --with-mongodb-zlib=bundled ';
         return clean_spaces($arg);
     }
+
+    public function getExtraEnv(): array
+    {
+        return ['CFLAGS' => '-std=c17'];
+    }
 }