[WIP] Add debug flags example gem

Author: sue445

ruby/testdata/example/ext/example/extconf.rb

@@ -12,5 +12,5 @@
 append_cflags("-fvisibility=hidden")
 
 ############ Appended for go native extension
-create_go_makefile("example/example")
+create_go_makefile("example/example", go_build_args: "-gcflags='all=-N -l'")
 ############ Appended for go native extension