[lit, lldbsuite] Update the lldbsuite to correctly run tests on windows and windows server

Summary:
The new script to run the lldbtests as part of lit invokes each test by calling dotest.py, however, we cannot rely on the system to always correctly interpret the script as python causing the tests to be unresolved on windows (at least). To fix this, we need to make sure that the first parameter in the command line is the python executable itself.

In Makefile.rules, there are a number of windows specific definitions that rely on the HOST_OS being set as Windows_NT but the logic detecting the OS currently does not detect server versions of windows correctly. This change updates the logic to detect windows server as well.

Reviewers: asmith, labath, JDevlieghere, zturner

Reviewed By: JDevlieghere, zturner

Subscribers: zturner, llvm-commits

Differential Revision: https://reviews.llvm.org/D46020

llvm-svn: 330740