gdbremote testing: added regex support to match packets and propagate/test...

gdbremote testing: added regex support to match packets and propagate/test against previously stored matches.

Added a test validating that $qC after an inferior launch via $A
returns a thread id that an immediately followig $? reports for the
active thread. This is currently skipped on debugserver (the thread
ids don't match) and isn't yet implemented in TOT for llgs.

llvm-svn: 208061