merge revision(s) r45066: [Backport #9550]

	* ext/socket/ancdata.c (bsock_sendmsg_internal): only retry on error
	  (bsock_recvmsg_internal): ditto

	* test/socket/test_unix.rb: test above for infinite loop


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@45098 b2dd03c8-39d4-4d8f-98ff-823fe69b080e