Copy of similar change in upstream BLIS (843a5e8) to fix issues
https://github.com/flame/blis/issues/873 and
https://github.com/amd/blis/issues/50
Details:
- Previously, `<omp.h>` was included in `bli_thrcomm_openmp.h` so that the
framework could access the necessary OpenMP functions.
- As @melven reported (#873), this causes issues when `blis.h` is included
in C++ code since the `<omp.h>` include happens with `extern "C"`.
- Move the include from the header to the necessary .c files so that it
does not "pollute" `blis.h`.
Thanks to @DaAwesomeP and @bartoldeman for reporting this issue in
AOCL BLIS
AMD-Internal: [CPUPL-7303]
011c75dddb