merge revision(s) 44433: [Backport #9299]

	* proc.c: Having any mandatory keyword argument increases min arity
	  [#9299]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@45226 b2dd03c8-39d4-4d8f-98ff-823fe69b080e