BaseTools: Fix Python SyntaxWarning

- Windows paths must be escaped
- Regex should use raw strings

Signed-off-by: Tim Crawford <tcrawford@system76.com>

BaseTools/Source/Python/Common/Misc.py

@@ -1926,4 +1926,4 @@ def CopyDict(ori_dict):
 # Remove the c/c++ comments: // and /* */
 #
 def RemoveCComments(ctext):
-    return re.sub('//.*?\n|/\\*.*?\\*/', '\n', ctext, flags=re.S)
+    return re.sub(r'//.*?\n|/\\*.*?\\*/', '\n', ctext, flags=re.S)