Add cmake cache for enabling sccache while building with the new runtime
build when sccache is available.
To build with sccache, pass the `sccache.cmake`
```
cmake \
-B build \
-S Runtime/Core \
-C Runtimes/Core/cmake/cache/sccache.cmake
```
Optimization remarks were always emitted on Darwin but not on the other
platforms and were forced to use the bitstream format. Adding a flag to
enable or disable them as desired and specify the desired output format.
Fixes: https://github.com/swiftlang/swift/issues/79279
The main goal for now is to have this building, with little
concern about matching the build flags used currently.
Keep it disabled by default on Apple platforms.
Addresses rdar://143151393
In some configurations, libraries are installed under
`<install-prefix>/{libdir}/swift/<platform>/<arch>` and module content
is installed under `<install-prefix>/{libdir}/swift/<platform>`.
This also accounts for the fact that Swift currently looks under
`<install-prefix>/{libdir}/swift_static/**` for the static stdlib
builds.
...building the stdlib for Apple platforms.
For now we want to match the flags the existing configuration (which is
already accounted by the default values provided by CMake) -- in
particular the generation of full symbols and usage of whole module
optimization.
Addresses rdar://142620659
