Log Message:
ruby-redmine42: Various portability fixes.

Use pax for install rather than hand-crafted find -exec which wasn't working
correctly.  Don't find ".*" with -type d and then rm, you might end up
removing ".destdir/".  And fix REPLACE_RUBY which can't have worked due to
incorrect paths as well as coming after including modules.mk (so will have
been a NOP).