For issue #4507, "pkg-config support breaks DESTDIR install", prepend
$(DESTDIR) to pkg-config file paths. 'make DESTDIR=/foo install' now
installs pkg-config files within /foo, as intended.

* build/generator/templates/build-outputs.mk.ezt: Prepend $(DESTDIR) to
   pkg-config files.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1597985 13f79535-47bb-0310-9956-ffa450edef68