Disable simbols on non-debug macos builds

Author: ignisf

ext/libv8/builder.rb

@@ -13,6 +13,7 @@ class Builder
 
     def gn_args
       %W(is_debug=#{debug_build? ? 'true' : 'false'}
+         symbol_level=#{debug_build? ? '-1' : '0'}
          is_component_build=false
          v8_monolithic=true
          v8_use_external_startup_data=false
@@ -27,6 +28,7 @@ def generate_gn_args
     end
 
     def debug_build?
+      puts enable_config('debug').inspect
       enable_config('debug')
     end
 
@@ -37,7 +39,7 @@ def build_libv8!
         puts 'Beginning compilation. This will take some time.'
         generate_gn_args
 
-        system 'ninja -v -C out.gn/libv8 v8_monolith'
+        system 'ninja -j 4 -v -C out.gn/libv8 v8_monolith'
       end
       return $?.exitstatus
     end