Run OpenCL tests only when there are changes to its source

[serban-nicusor-toptal]

Summary

Run OpenCL CPU tests in the pipeline only if there are changes to 'stan/math/opencl' or 'test/unit/math/opencl'.

Tests

No new tests.

Side Effects

No.

Release notes

Checklist

• Math issue #(issue number)
  Run OpenCL tests only when there are changes to its source #2402

• Copyright holder: (fill in copyright holder information)

  The copyright holder is typically you or your assignee, such as a university or company. By submitting this pull request, the copyright holder is agreeing to the license the submitted work under the following licenses: Toptal
  - Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
  - Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

• the basic tests are passing

  • unit tests pass (to run, use: ./runTests.py test/unit)
  • header checks pass, (make test-headers)
  • dependencies checks pass, (make test-math-dependencies)
  • docs build, (make doxygen)
  • code passes the built in C++ standards checks (make cpplint)

• the code is written in idiomatic C++ and changes are documented in the doxygen

• the new changes are tested

[stan-buildbot]

---

Name	Old Result	New Result	Ratio	Performance change( 1 - new / old )
gp_pois_regr/gp_pois_regr.stan	3.4	3.48	0.98	-2.47% slower
low_dim_corr_gauss/low_dim_corr_gauss.stan	0.02	0.02	1.0	-0.03% slower
eight_schools/eight_schools.stan	0.12	0.11	1.03	3.3% faster
gp_regr/gp_regr.stan	0.16	0.16	0.99	-0.64% slower
irt_2pl/irt_2pl.stan	5.23	5.23	1.0	0.12% faster
performance.compilation	90.23	88.65	1.02	1.75% faster
low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan	8.68	9.16	0.95	-5.58% slower
pkpd/one_comp_mm_elim_abs.stan	28.86	29.66	0.97	-2.75% slower
sir/sir.stan	130.86	133.6	0.98	-2.1% slower
gp_regr/gen_gp_data.stan	0.04	0.04	0.99	-1.4% slower
low_dim_gauss_mix/low_dim_gauss_mix.stan	2.98	3.02	0.99	-1.42% slower
pkpd/sim_one_comp_mm_elim_abs.stan	0.38	0.39	0.97	-2.69% slower
arK/arK.stan	1.8	1.79	1.0	0.22% faster
arma/arma.stan	0.74	0.75	0.99	-0.75% slower
garch/garch.stan	0.58	0.59	0.99	-1.08% slower
Mean result: 0.990145419859

---

Jenkins Console Log
Blue Ocean
Commit hash: cd8c689

---

Machine information

ProductName: Mac OS X ProductVersion: 10.11.6 BuildVersion: 15G22010

CPU:
Intel(R) Xeon(R) CPU E5-1680 v2 @ 3.00GHz

G++:
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.6.0
Thread model: posix

Clang:
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.6.0
Thread model: posix

[rok-cesnovar]

Thanks!