Bug#1013041: source-highlight: ftbfs with GCC-12

[Graham Inggs]

Control: tags -1 + fixed-upstream patch

There's already an upstream commit [1] that fixes this issue.


[1] 
https://git.savannah.gnu.org/cgit/src-highlite.git/commit/?id=ab9fe5cb9b85c5afab94f2a7f4b6d7d473c14ee9