Update some CI jobs

* Move ThreadSanitizer job to the scheduled jobs (once a day): all our tests
  are intrinsically mono-thread and this job takes quite some time

* Two explicit jobs to test LTO and Gold linker, used by oss-fuzz

* Two explicit jobs for Windows (with msys2)

* Run address sanitizer only on the 4 main jobs: newest/oldest gcc/clang

* Reduce the time used by fuzzing jobs. Note that oss-fuzz is
  continuosly fuzzing our code!

* Move the no x86_64 jobs to a dedicated file

This way, the main matrix is a little bit simpler and the CI jobs last a
little shorter