History for mbed-os / events / tests / UNITTESTS / doubles / fakes / CMakeLists.txt

Use the `--coverage` option instead of manually linking to gcov, as some
host platforms (like macOS, FreeBSD) don't have gcov by default and use
an llvm equivalent instead.

Previously events fakes as part of UNITTESTS/fakes, this PR moves
events fakes to events double directory to make events stubs
to be self-contained.