libxml2 arg typo

Author: el7cosmos

src/SPC/builder/unix/library/libxml2.php

@@ -30,7 +30,7 @@ public function build(): void
             );
 
         if ($this instanceof LinuxLibraryBase) {
-            $cmake->addConfigureArgs('-DIconv_IS_BUILD_IN=OFF');
+            $cmake->addConfigureArgs('-DIconv_IS_BUILT_IN=OFF');
         }
 
         $cmake->build();