Moving this helper CMake file to the centralized Meta/CMake folder helps
to get a better grasp on what extra files are required for the build,
and what files are generated.
While we're at it, don't use add_compile_definitions for
ENABLE_UNICODE_DATA, which only needs to be seen by LibUnicode sources.
There is a bit of a race here between the Fuzzer and non-Fuzzer Lagom
builds. If the Unicode caches are empty, and the Fuzzer build completes
first, then the UCD and CLDR directories will be empty or won't exist.
Skip handling the Unicode caches for this build.
Caches on Azure are immutable - so if a cache changes, but its key does
not, then the cache is not updated. Include a timestamp in the ccache
key so that we always push an updated cache from the master branch. Then
use a subkey without the timestamp to pull the cache.
We use a similar trick on GitHub Actions.
We were over-hashing for the GNU build on GitHub Actions by including
the LLVM patch as well. The GNU Toolchain doesn't care about our LLVM
patches.
For Azure, fix the inversion of the condition for which jobs check which
Build*.sh script, and add the Toolchain patch files to the cache
hash calculation.
