BLT cmake language suport initialization difference between cuda and hip

[cyrush]

BLT calls enable_language(cuda) when cuda is on:

blt/cmake/thirdparty/SetupCUDA.cmake

Line 67 in 8c22999

enable_language(CUDA)

However, it doesn't call: enable_language(hip) when hip is on.

We should be consistent.

[cyrush]

And fun fact:

enable_language(HIP)

(don't tread the lowercase trail)

[skyreflectedinmirrors]

Also, as of the latest release, the HIP smoke tests are .cpp files (i.e., they expect to be compiled using e.g., CMAKE_CXX_COMPILER=hipcc, or amdclang++ with the right flags set).

If I get around to it, I might take a pass at using HIP language support in BLT.

[skyreflectedinmirrors]

A few question for y'all on HIP-Lang support:

• Would you expect there to be a new BLT target -- i.e., separate from the existing blt::hip / blt::hip_runtime -- for source files that use the HIP-language (as opposed to hipcc-as-CXX), which would add HIP as the target language to all the SOURCES for that test (etc.) -- this is not ideal, imo as you can have a target that has both CXX/HIP/etc. language files -- OR
• Would you expect that HIP-language source files conform to the CMAKE_HIP_SOURCE_FILE_EXTENSIONS (i.e., be named source.hip), and/or explicitly set the target language

Additionally, do you think BLT should allow mixing of the 'legacy' HIP target and 'HIP-Language' targets at the same time?