Delete TestLLVM.py

This was added to workaround a limitation in LLVM's implementation
of getting the current user's home directory, since it would
only look at the value of $HOME, but we did not want to rely
on that being set so we would also look in the password database.

Adding the ability to look in the password database to LLVM was
a straightforward patch that was submitted in r298513, so since
that is done this test is no longer needed.

llvm-svn: 298519