MapWindowsToCygwin returns Windows path #1498

Another issue like #1418 that can cause wrong paths to be returned from MapWindowsToCygwin.

If LaunchCygPathAndReadResult fails, due to the five second timeout, MapWindowsToCygwin will return the original Windows path. This happened to a coworker of mine because the name resolution to our domain controller is sometimes extremely slow, which causes the startup of many Cygwin programs to take a lot longer than usual.

The symptom was an error message when launching the debugger. It will read somewhat like this:

GDB failed with message:
C:Dir1Dir2PathToTheExecutable: No such file or directory.

I'd like to receive a proper error when LaunchCygPathAndReadResult times out. It took us a lot of time and digging around to figure out why GDB was reporting such a path, only to find out that, ultimately, the MIEngine was the root cause for this error.