Added gdb remote test for one valid qRegisterInfo result.

Checks that at at least qRegisterInfo0 responds with a valid
register info reply packet.  The packet is parsed and validates
that all keys come from the documented set of valid keys.  It
then validates that a minimum set of expected keys
are present in the returned packet.

This test is set to pass on debugserver and fail on llgs TOT.

llvm-svn: 209109