merge revision(s) r45190,r45202,r45204,r45713: [Backport #9586]

	configure.in: define SET_THREAD_NAME

	* configure.in (SET_THREAD_NAME): define according to
  pthread_setname_np variations.
	* configure.in: correct pthread_setname_np's prototype on NetBSD.
	  [Bug #9586]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@45867 b2dd03c8-39d4-4d8f-98ff-823fe69b080e