gfauto: use --fuzzer-pass-validation (#1048)
gfauto: use --fuzzer-pass-validation (#1048)

When running spirv-fuzz, use `--fuzzer-pass-validation` to detect validation errors after each fuzzer pass (i.e. spirv-fuzz bugs).
google/graphicsfuzz,google/graphicsfuzz,google/graphicsfuzz,google/graphicsfuzz,google/graphicsfuzz,google/graphicsfuzz,google/graphicsfuzz