* common.mk (ext/ripper/ripper.c): pass build directory as VPATH.

* ext/ripper/depend (.y.c): use VPATH for y.tab.c.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48493 b2dd03c8-39d4-4d8f-98ff-823fe69b080e