Bug#1051680: mesa: switch LLVM major version to 16

[Simon McVittie]

Source: mesa
Version: 23.1.6-1
Severity: wishlist
X-Debbugs-Cc: llvm-toolchain-16 at packages.debian.org
Control: block 1050070 by -1

According to #1050071, #1050070 and #1050069, the LLVM maintainers want
to switch the default LLVM major version from 14 to 16, and remove versions
14 and 15.

Mesa currently uses LLVM 15 rather than the default 14. Should it move
to 16 in testing/unstable, ahead of the default changing?

    smcv