[vcpkg] vcpkg_configure_meson: Support macOS cross-compile

[past-due]

Describe the pull request

NOTE: Depends on #15659 (the first 3 commits in this PR are from #15659, for running CI) - now merged!

Based on discussion on Discord with @ras0219, this takes the approach of a minimal fix to the meson cross-compile config.

While this fixes cross-compiling many meson-based ports, there is one exception:

Meson-based ports that require "native" architecture tools to be built as part of their build process may still have issues. But as @ras0219 noted (on Discord), that is best fixed by port-level fixes after PR #15424 is merged that take advantage of that new "host triplet dependency" functionality. Regardless, this fix is needed for the rest.

• What does your PR fix?

Fixes arm64-osx cross-compile of meson-based ports.

(Building meson-based ports for arm64-osx would previously build them for the native architecture - i.e. building harfbuzz:arm64-osx on an Intel 64-bit Mac, would seemingly succeed but actually build an x86_64 architecture library.)

• Which triplets are supported/not supported? Have you updated the CI baseline?

arm64-osx

[JackBoosY]

cc @Neumann-A for review this PR.

[past-due]

Rebased on top of the latest master branch (which has now merged #15659).

[past-due]

@ras0219-msft @JackBoosY Just for clarity, I would like to encourage the merging of this PR as-is. (Additional port fixes will depend on #15424, but I feel that those are out-of-scope for this PR and best left for a subsequent PR.)

This small change fixes a number of ports (harfbuzz:arm64-osx, and everything that depends on it, being a very important one).

[JackBoosY]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[JackBoosY]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[past-due]

@JackBoosY x86_windows failure appears to be unrelated to this PR:

Found the following errors:
Error: While reading versions for port log4cpp from file: C:\a\1\s\versions\l-\log4cpp.json
       Version `2.9.1#4` was not found in versions file.
       Run:

           vcpkg x-add-version log4cpp

       to add the new port version.

To attempt to resolve all errors at once, run:

    vcpkg x-add-version --all

[past-due]

All seems to check out with the new regex, and I'm pretty happy with that as the solution. (It fixes many other issues as well with splitting CFLAGS / CXXFLAGS.)

@Neumann-A, @ras0219-msft?

[ras0219-msft]

LGTM, this is a clear improvement over the status quo. I'm sure there will be some additional edge cases found in the future, but I don't think that is worth holding up the improvement now.