[fuzzing] Add support for host fuzzers

This CL adds a group of host fuzzers to the fuzz package template to be
built only when a fuzz package is selected and the package has
`fuzz_host=true`.

SEC-44

Tests: Set and built with and without --fuzz-with asan
Change-Id: Ifd88357ff11baadd6c844d5b12e8d13369eae703
1 file changed