nits: Move to generate_ldflags

Author: sue445

_gem/lib/go_gem/rake_task.rb

@@ -110,7 +110,6 @@ def self.build_env_vars
         cflags.gsub!("-Wsuggest-attribute=format", "")
         cflags.gsub!("-Wold-style-definition", "")
         cflags.gsub!("-Wsuggest-attribute=noreturn", "")
-        ldflags.gsub!("-Wl,--unresolved-symbols=ignore-all", "")
       end
 
       # FIXME: Workaround for Alpine

_gem/lib/go_gem/util.rb

@@ -26,6 +26,9 @@ def self.generate_ldflags
         ldflags << " -undefined dynamic_lookup"
       end
 
+      # FIXME: Workaround for Ubuntu (GitHub Actions)
+      ldflags.gsub!("-Wl,--unresolved-symbols=ignore-all", "") if RUBY_PLATFORM =~ /linux/i
+
       ldflags
     end
   end