force same c++ compiler for unref

2 jobs for particles0 in 26 minutes and 47 seconds
latest
Status Job ID Name Coverage
  Test
failed #9054
makedg

00:26:47

passed #9055
win64

00:06:53

 
Name Stage Failure
failed
makedg Test There is an unknown failure, please try again
93% tests passed, 3 tests failed out of 42

Total Test time (real) = 1282.59 sec

The following tests FAILED:
33 - modules/slimParticles/tests/parTracker_basic (Failed)
34 - modules/slimParticles/tests/parTracker_wind (Failed)
35 - modules/slimParticles/tests/parTracker_seedWithDof (Failed)
ERROR: Build failed: exit code 1