The directory php-5.2.5/ is obtained by
bzip2 -dc php-5.2.5.tar.bz2 | tar xvf -
find php-5.2.5/ | grep -v "/tests/" | xargs rm -f
cd php-5.2.5/; cleanlinks

The first command unpack the php-5.2.5 source package.
The second command removes any files that do not have "/tests" in their
paths. The assumption is that all the test files (.phpt files and test
data files) must have "/tests/" in their paths.
The third step uses the program cleanlinks to remove dangling symbolic
links and empty directories.

This leaves us perhaps with a little more than necessary for hphp testing
but we won't miss any.