This reverts commit c6bf5d47240cebef356276e369881e855dbe7e6d.
Related to D2264: When multi process opencl kernel compilation is in place single-program compiles slower then multi-program. c6bf5d47240cebef356276e369881e855dbe7e6d was created as single-program compiled faster, but this is not the case anymore. So let's revert this change. Production scenes like victor and barbershop even render quicker.
Change in Cycles OpenCL compilation times
job | scene_name | compilation_time | render_timeBaseline | empty | 22.73 | 20.63
T61514 | empty | 10.63 | 21.06
Baseline | bmw | 56.44 | 191.00
T61514 | bmw | 17.91 | 198.44
Baseline | fishycat | 59.50 | 393.48
T61514 | fishycat | 19.57 | 394.20
Baseline | barbershop | 212.28 | 1623.53
T61514 | barbershop | 54.10 | 1188.16
Baseline | victor | 67.51 | 1459.80
T61514 | victor | 22.06 | 1381.58
Baseline | classroom | 51.46 | 341.23
T61514 | classroom | 17.55 | 341.08
Baseline | koro | 62.48 | 475.96
T61514 | koro | 18.92 | 472.43
Baseline | pavillion | 54.37 | 903.48
T61514 | pavillion | 17.43 | 905.77
Baseline | splash279 | 47.43 | 52.92
T61514 | splash279 | 16.48 | 55.26
Baseline | volume_emission | 145.22 | 62.38
T61514 | volume_emission | 36.22 | 62.59