Here are a few patches to tweak our CI sanitizer setup. The first one
hopefully increases coverage. The other two just aim to reduce the
amount of CPU we use.

  [1/3]: ci: use clang for ASan/UBSan checks
  [2/3]: ci: run ASan/UBSan in a single job
  [3/3]: ci: drop linux-clang job

 .github/workflows/main.yml | 10 ++--------
 ci/lib.sh                  |  7 ++-----
 2 files changed, 4 insertions(+), 13 deletions(-)

-Peff