Make :dot-graphs genrule quiet 
Make :dot-graphs genrule quiet 

The output of `which dot` is not a helpful diagnostic
message; so discard it in the test whether dot is installed
on the given system.

--
Change-Id: Ic6597a517cafe99796a9c109e3844c1fa56c8c97
Reviewed-on: https://cr.bazel.build/9120
PiperOrigin-RevId: 149002252
MOS_MIGRATED_REVID=149002252

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