signal.c: adjust style

* signal.c (rb_sigaltstack_size, ruby_abort): adjust style,
  procnames-start-lines.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42916 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2013-09-12

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42917 b2dd03c8-39d4-4d8f-98ff-823fe69b080e