[lit] Remove setting of the target-windows feature

[mstorsjo]

Summary

No other OSes use a target-<os> feature, and no tests (rightfully) depend on it. (This depends on D68449 to land before.)

This is an alternative to D68135. (The diff is made on top of it for practical reasons.)

[mstorsjo]

Ping @rnk - we should either go with this, or D68135.

[rnk]

lgtm

llvm/utils/lit/lit/llvm/config.py

def __init__(self, lit_config, config):
         if target_triple:
             if re.match(r'^x86_64.*-apple', target_triple):
                 host_cxx = getattr(config, 'host_cxx', None)
                 if 'address' in sanitizers and self.get_clang_has_lsan(host_cxx, target_triple):
                     self.with_environment(
                         'ASAN_OPTIONS', 'detect_leaks=1', append_path=True)
             if re.match(r'^x86_64.*-linux', target_triple):
                 features.add('x86_64-linux')
-            if re.match(r'.*-windows-msvc$', target_triple):
-                features.add('target-windows')
             if re.match(r'^i.86.*', target_triple):
                 features.add('target-x86')
             elif re.match(r'^x86_64.*', target_triple):
                 features.add('target-x86_64')
 
         use_gmalloc = lit_config.params.get('use_gmalloc', None)
         if lit.util.pythonize_bool(use_gmalloc):
             # Allow use of an explicit path for gmalloc library.