Reinstate quotes around the path to python that I accidentaly removed…

… in r335330

This broke users with spaces in the path, like C:\Program Files\Python

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@335382 91177308-0d34-0410-b5e6-96231b3b80d8

test/lit.cfg.py

@@ -70,7 +70,7 @@
 llvm_config.add_tool_substitutions(tools, tool_dirs)
 
 config.substitutions.append(
-    ('%hmaptool', '%s %s' % (config.python_executable,
+    ('%hmaptool', "'%s' %s" % (config.python_executable,
                              os.path.join(config.llvm_tools_dir, 'hmaptool'))))
 
 # Plugins (loadable modules)