Added gdbremote protocol test for $p and returned data size.

Each register returned by $qRegisterInfo is tested that it's
$p register read returns a representation that is the correct byte size
as indicated by $qRegisterInfo.

Currently enabled for debugserver, disabled for llgs.

The llgs branch will use this to verify $p implementation.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@209452 91177308-0d34-0410-b5e6-96231b3b80d8