add ext-decimal

src/SPC/builder/unix/library/libmpdec.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SPC\builder\unix\library;
+
+use SPC\util\executor\UnixAutoconfExecutor;
+
+trait libmpdec
+{
+    protected function build(): void
+    {
+        UnixAutoconfExecutor::create($this)
+            ->configure('--disable-cxx --disable-shared --enable-static')
+            ->make();
+    }
+}