[test_script] Add specific test for legends in histograms

4 jobs for histlegends in 9 minutes and 4 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Build
passed #140501
docker
build_linux_27

00:07:35

86.0%
passed #140502
docker
build_linux_36

00:07:35

86.0%
passed #140503
macosx
build_macosx_27

00:08:57

86.0%
passed #140504
macosx
build_macosx_36

00:08:22

86.0%