[test] Update STREAM benchmark test

[sekelle]

-Cray cc OpenMP flag change to -fopenmp
-need to set the Slurm flag --hint=nomultithread to get good performance on 2-socket systems

[sekelle]

`FAILURE INFO for StreamTest

• System partition: kesch:cn

• Environment: PrgEnv-gnu

• Stage directory: None

• Job type: batch job (id=-1)

• Maintainers: ['RS', 'VK']

• Failing phase: setup

• Reason: environ error: could not show module 'gmvapich2/17.02_cuda_8.0_gdr': command 'modulecmd python show gmvapich2/17.02_cuda_8.0_gdr' failed with exit code 0:

=== STDOUT ===

=== STDERR ===

ModuleCmd_Display.c(151):ERROR:105: Unable to locate a modulefile for 'gmvapich2/17.02_cuda_8.0_gdr'`

seems unrelated to this PR

[vkarak]

@sebkelle1 Config for Kesch is broken.

[vkarak]

Can you

[vkarak]

Please update

[pep8speaks]

Hello @sebkelle1, Thank you for updating!

Cheers! There are no PEP8 issues in this Pull Request!Do see the ReFrame Coding Style Guide

Comment last updated at 2019-07-18 14:02:10 UTC

[vkarak]

@jenkins-cscs retry daint kesch

[vkarak]

@sebkelle1 Test fails on Kesch. Can you have a look please?

[codecov-io]

Codecov Report

Merging #850 into master will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #850      +/-   ##
==========================================
+ Coverage   91.65%   91.66%   +<.01%     
==========================================
  Files          80       80              
  Lines       10308    10318      +10     
==========================================
+ Hits         9448     9458      +10     
  Misses        860      860

Impacted Files	Coverage Δ
unittests/test_pipeline.py	97.39% <0%> (+0.06%)	⬆️

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