Fix gdb-remote qMemoryRegionInfo unit tests for xml-enabled builds

In case we are building with xml enabled, the GetMemoryRegionInfo
function will send extra packets to query te extended memory map, which
the tests were not expecting.

Add an expectation for this to the test. Right now, it's just a basic
one which pretends we don't support the extension, however, it would be
also interesting the add a test which verifies the extension-enabled
case.

I also noticed that the test does a pretty lousy job of validating the
returned memory region info, so I add a couple of extra assertions to
improve that.

llvm-svn: 331374