get_maintainer.pl: Teach brace expansion

get_maintainer.pl: Teach brace expansion

Simpler non-nested brace expansion.

Some entries in the MAINTAINER are not understood by the script, the
ones that contain {,}. This patch fixes it.

This will convert brace expansion style use in MAINTAINER into a regex
that get_maintainer.pl can use to match a path again a maintainer
section.

It is done by using two different regex, the first one will take care of
converting ',' inside '{}' to a '|', one by one, as long as there is at
least two commas. The second regex will do the final convertion of '{,}'
to '(|)'.

With the patch, the right maintainers are displayed, instead of "THE
REST" maintainers, when using the following command for e.g.
$ ./scripts/get_maintainer.pl -f docs/misc/kconfig.txt

The patch also get rid of the warnings, with recent perl:
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/^docs/misc/kconfig{ <-- HERE ,-language}\.txt/ at ./scripts/get_maintainer.pl line 731.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Tested-by: Doug Goldstein <cardoe@cardoe.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>