192c549d40
* add support for compiling all backends
also include the logic to select backends either based on user requests
or through some heuristics
* checkpoint for compiling all backends
* final checkpoint
all tests seem to pass when compiling all three backends simultaneasly
and forcing to use any of the three Backends.
* update PR to new envvar system
[ROCm/rocshmem commit: a1269e3db5]