Patch utility support regexp in patchfile

Rpatch is a patch utility, more tolerant than GNU patch. It will ignore
changes of blank lines and white spaces, and what's more you can write
regexp ("RE: " and "RE:-") in patch file to match lines.

 * Use "RE: " with a regexp to match unchanged line.
 * Use "RE:-" with a regexp to match removed line.
 * Use "@@" to starts a new patch hunk only and use it's text as
   description for the hunk only.

Signed-off-by: Jiang Xin <worldhello.net@gmail.com>