Add compile_commands.json to .gitignore
Add compile_commands.json to .gitignore

Change-Id: Ice093f541798da8fa4aa480b5059c85df2eb84ef
Reviewed-on: http://gerrit.cloudera.org:8080/298
Reviewed-by: Martin Grund <2546548d516fa64c411fde8242af35f3f80ad31f@cloudera.com>
Tested-by: Internal Jenkins

cloudera/Impala,michaelhkw/incubator-impala,cloudera/Impala,michaelhkw/incubator-impala,cloudera/Impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala