bring back openmp for musl, add TODO to add it back in on glibc

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

@@ -18,8 +18,9 @@ trait imagemagick
      */
     protected function build(): void
     {
-        // TODO: imagemagick build with bzip2 failed with bugs, we need to fix it in the future
-        $extra = '--without-jxl --without-x --disable-openmp ';
+        // TODO: glibc rh 10 toolset's libgomp.a was built without -fPIC -fPIE so we can't use openmp without depending on libgomp.so
+        $openmp = getenv('SPC_LIBC') === 'musl' ? '--enable-openmp' : '--disable-openmp';
+        $extra = "--without-jxl --without-x {$openmp} ";
         $required_libs = '';
         $optional_libs = [
             'libzip' => 'zip',