Fixed intermittent failures in TestGdbRemote*/TestLldbGdbServer

test/tools/lldb-server/commandline/Test* were actually executing in
their parent directory. This looks fine at first because they aren't
compiling an inferior executable.

Unfortunately, they still call "make clean" during their cleanup,
which is likely causing all kinds of havok in tests running in the
parent directory

Differential Revision: http://reviews.llvm.org/D9869

llvm-svn: 237932