Add spx extension support (#501)

src/SPC/builder/extension/spx.php

@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SPC\builder\extension;
+
+use SPC\builder\Extension;
+use SPC\exception\WrongUsageException;
+use SPC\util\CustomExt;
+
+#[CustomExt('spx')]
+class spx extends Extension
+{
+    /**
+     * @throws WrongUsageException
+     */
+    public function validate(): void
+    {
+        if ($this->builder->getOption('enable-zts')) {
+            throw new WrongUsageException('ext-spx is not thread safe, do not build it with ZTS builds');
+        }
+    }
+
+    public function getUnixConfigureArg(): string
+    {
+        $arg = '--enable-spx';
+        if ($this->builder->getExt('zlib') === null) {
+            $arg .= ' --with-zlib-dir=' . BUILD_ROOT_PATH;
+        }
+        return $arg;
+    }
+}