kdesrc-build: Make testsuite $HOME-compliant.

Pino Toscano noted that there were several tests failing on his system
after (well, and before ;) he changed the source directory setting in
the test suite to be under the home directory.

Indeed he is right, although I removed references to my home directory
when uploading my test suite, I did not remove references to my source
and build directories, which naturally did not contain svn sources on
Pino's system, which caused several tests to fail.

Now the testsuite will do a svn checkout (of kdesupport at this point as
I feel it is most likely to hang out in svn) before running tests on
functions requiring a svn source directory. The checkout is constrained
to avoid checking out any files or referencing any external svn
checkouts and is only run when running the test suite, so hopefully this
doesn't represent any significant load on the KDE svn servers.

In addition the base directory for all operations is under a temporary
directory, cleaned up when the test suite completes. Right now the
temporary directory is created under the normal temp dir (/tmp on my
system), the Temp::File docs seem to indicate this can be changed by
specifying DIR => /path/to/dir when running tempdir() if desired.

Finally, I ended up adding a test for the directory creation function in
the process of testing the test suite, which I left it because it's a
good idea anyways.

All tests pass on my system now with these changes, hopefully that will
be the case elsewhere.