BaseTools: Fix raw strings containing valid escape characters

Fixes raw regex strings that contain valid (and purposeful) escape
characters as they are being treated as individual characters rather
than the single escaped character they represent (i.e. '\t' is being
treated as a '\' and a 't' rather than a single tab character).

Signed-off-by: Joey Vagedes <joey.vagedes@gmail.com>
Cc: Rebecca Cran <rebecca@bsdio.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Yuwei Chen <yuwei.chen@intel.com>
Reviewed-by: Yuwei Chen <yuwei.chen@intel.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>

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(r'//.*?\n|/\*.*?\*/', '\n', ctext, flags=re.S)
+    return re.sub('//.*?\n|/\\*.*?\\*/', '\n', ctext, flags=re.S)