This commit should largele be a NOOP as it only adds support
for DESTDIR undefined. This does allow us to start testing
ports with DESTDIR set, but this is as of yet not supported.
Although this has been extensively tested on pointyhat, this
is a very intrusive change and some cases may have been
overlooked. Please contact Gabor and me if you find any.
PR: 100555
Submitted by: gabor
Sponsored by: Google Summer of Code 2006
