Instead of calling `google::InitGoogleLogging()` directly, introduce an
indirection via a new utility library. After this change, Sandboxed API
should consistently use `sapi::InitLogging()` everywhere.
For now, `sapi::InitLogging()` simply calls its glog equivalent. However,
this enables us to migrate away from the gflags dependency and use Abseil
flags. Once a follow-up change lands, `sapi::InitLogging()` will instead
initialize the google logging library with flags defined from Aseil.
Later still, once Abseil releases logging, we can then drop the glog
dependency entirely.
PiperOrigin-RevId: 445363592
Change-Id: Ia23a7dc88b8ffe65a422ea4d5233bba7bdd1303a
This updates the mininum required version of CMake to 3.13, which is
present in Debian Buster.
At the same time, move all of our dependency handling to use
`FetchContent_Declare()`, `FetchContent_Populate()` and
`FetchContent_MakeAvailable()`. Since the latter was ony introduced in
3.14, provide a simple "polyfill" implementation for that.
As an added benefit, the configure step for libffi and libunwind will
now not be re-run every time the `CMakeLists.txt` changes.
Other changes:
- Explicitly spell out that we're testing up to 3.22 in
`cmake_minimum_version()`
- Rename `check_target()` to `sapi_check_target()` to avoid conflicts
with Abseil.
