Fix handling of escape characters in regexs and hence fix python
Deprecation warnings which will be problematic in python 3.8.
Note that some show up as:
"""
meta/classes/package.bbclass:1293: DeprecationWarning: invalid escape sequence \.
"""
where the problem isn't on 1293 in package.bbclass but in some _prepend to a
package.bbclass function in a different file like mesa.inc, often from
do_package_split() calls.
(From OE-Core rev: 4b1c0c7d5525fc4cea9e0f02ec54e92a6fbc6199)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
cd4b8a8553