dl/dl.h: suppress warning

* ext/dl/dl.h (dlopen): suppress unused-but-set-variable warning.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40119 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
ext/-test-/win32/dln: remove static library

* ext/-test-/win32/dln/extconf.rb: remove static library too at clean.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40120 b2dd03c8-39d4-4d8f-98ff-823fe69b080e