CMake ENABLE_TARGET_OPENMP doesn't actually enable OpenMP resources

[abbotts]

The CMake -DENABLE_TARGET_OPENMP flag doesn't look like it actually has any effect. Although this define has the same name, there isn't actually any CMake machinery to turn the config flag into the CPP define

camp/include/camp/defines.hpp

Line 109 in 72e3f39

#if defined(ENABLE_TARGET_OPENMP)

I think this is the root cause of LLNL/RAJA#1111

Because CAMP's build is so bare-bones I don't see an easy solution that I can just implement quickly, other than backout out #46 (which seems like it would break something else). The proper solution would probably involve #41 and some machinery to add OpenMP flags.

[trws]

If you have a look in the ci-all-the-things branch, you'll find the version I'm working on to build with BLT, which should fix that. That should upstream shortly once I get the last of the clang bugs on the azure pipeline squashed out of it.

[abbotts]

ci-all-the-things does add -fopenmp with -DENABLE_OPENMP via blt, which is a step forward. I don't think it solves the ENABLE_TARGET_OPENMP problem yet, though.

[abbotts]

This CPP define is now CAMP_ENABLE_TARGET_OPENMP, and is correctly set by the CMake define of the same name, so this issue is fixed.

[barracuda156]

@abbotts Apparently not: LLNL/CHAI#231