This reverts commit 68b1abf77f.
The warnings are valuable and shouldn't be cast aside.
As of 8f509f1, we special case macOS and don't set -fno-sanitize-recover
to allow CI to succeed.
In the future, this could be made stricter again by only suppressing
known bugs, which ideally should also be fixed or reported upstream.
Previously sanitizer flags were set unconditionally for
all code, including that of external libraries.
Set them only for targets in src/, tests/ and exposed/.
Unfortunately, the linker equivalent to add_compile_options,
add_link_options, is only available for CMake version >= 3.13.
So add the sanitizer flags manually to each target's linker options.