Allow forcing color clang diagnostics with an env var
Allow forcing color clang diagnostics with an env var

Change-Id: I3161d6dcc3715693771089351aadb29810c00fcc
Reviewed-on: http://gerrit.cloudera.org:8080/6619
Reviewed-by: Adar Dembo <866ca730bfc7f544e3ebce604ceeba4879f23df0@cloudera.com>
Tested-by: Kudu Jenkins

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