signal.c: unblock signal
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58353 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
signal.c: unblock signal
receive the same signal again. [ruby-core:79285] [Bug #13164]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58353 b2dd03c8-39d4-4d8f-98ff-823fe69b080e