[wasm-pic] Apply asyncify-relocatable to the wasmoptflags

Author: kateinoigakukun

lib/ruby_wasm/packager/core.rb

@@ -136,7 +136,7 @@ def derive_build
       build.crossruby.cflags = %w[-fPIC -fvisibility=default]
       if @packager.full_build_options[:target] != "wasm32-unknown-emscripten"
         build.crossruby.debugflags = %w[-g]
-        build.crossruby.wasmoptflags = %w[-O3 -g]
+        build.crossruby.wasmoptflags = %w[-O3 -g --pass-arg=asyncify-relocatable]
         build.crossruby.ldflags = %w[
           -Xlinker
           --stack-first