Suppress LLVM::tools/llvm-symbolizer/coff-dwarf.test for mingw, for now.

FIXME: Improve llvm-symbolizer, or rename the feature "system-windows".
llvm-svn: 249937

llvm/test/lit.cfg

@@ -443,7 +443,7 @@ if 'darwin' == sys.platform:
         config.available_features.add('fma3')
     sysctl_cmd.wait()
 
-if platform.system() in ['Windows']:
+if platform.system() in ['Windows'] and re.match(r'.*-win32$', config.target_triple):
     # For tests that require Windows to run.
     config.available_features.add('system-windows')