merge revision(s) r44756: [Backport #r44402]

	* configure.in: use $@ instead of $(.TARGET) because .TARGET is not
	  supported by GNU make.


git-svn-id: svn+ssh://svn.ruby-lang.org/ruby/branches/ruby_2_0_0@44769 b2dd03c8-39d4-4d8f-98ff-823fe69b080e