Currently, coverage builds fail on step 3 with:
```
Step #3: + rsync -avLkR --include '*.h' --include '*.cc' --include '*.hpp' --include '*.cpp' --include '*.c' --include '*/' --exclude '*' /tmp /workspace/out/coverage
Step #3: sending incremental file list
Step #3: symlink has no referent: "/tmp/tmp.BOH6TAB62E/ares/include/ares_build.h"
Step #3: symlink has no referent: "/tmp/tmp.BOH6TAB62E/ares/include/ares_dns.h"
Step #3: symlink has no referent: "/tmp/tmp.BOH6TAB62E/ares/include/ares.h"
Step #3: symlink has no referent: "/tmp/tmp.BOH6TAB62E/ares/include/ares_rules.h"
Step #3: symlink has no referent: "/tmp/tmp.BOH6TAB62E/ares/include/ares_version.h"
Step #3: symlink has no referent: "/tmp/tmp.BOH6TAB62E/include/sha1.c"
Step #3: symlink has no referent: "/tmp/tmp.BOH6TAB62E/include/gcm_nohw.c"
Step #3: symlink has no referent: "/tmp/tmp.BOH6TAB62E/include/digests.c"
...
```
Just exclude these files. Doubt they matter to us.
Ref: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=23621&q=esp-v2&can=2
Signed-off-by: Teju Nareddy <nareddyt@google.com>
[Example failure](https://oss-fuzz-build-logs.storage.googleapis.com/log-8eabbac0-bb8f-4f90-a840-f23efe427e0e.txt)
This only occurs on the fuzzers for some reason, not on Travis CI. Error is similar to https://github.com/bazelbuild/bazel/issues/5640.
Change spawn strategy to `sandboxed` to work around this. Not sure why it was `local` to begin with (other than a slight performance improvement).
Tested locally to ensure this spawn strategy will work.
```
python infra/helper.py build_fuzzers --sanitizer address --engine libfuzzer --architecture x86_64 esp-v2
```
Signed-off-by: Teju Nareddy <nareddyt@google.com>
Teju Nareddy