The current GCC branch will become 12.1.0, which will be the stable version of GCC when the next macOS version is released. There are some places in GCC that don’t handle darwin22 as a version, so we need to future-proof it (gcc/config.gcc and gcc/config/darwin-driver.c). We align that code with what Apple clang does, i.e. accept all potential major macOS versions until 99.

This patch also homogenises the handling of darwin version numbers, where the majority of places use darwin2*, but some used darwin2[0-9]*. Since there never was a darwin2.x version, the two are equivalent, and we prefer the simpler darwin2*

Bootstrapped and regtested on x86_64-apple-darwin21.
OK to commit?

FX