CMake's FindBLAS.cmake module looks for OpenMP when looking for a static
version of the OpenBLAS library. Even if it doesn't necessarily need
OpenMP for that library. Which can result in a couple of package not
being found messages, even though BLAS itself is found and is functional.

This is a pretty brute-force method for just silencing any output
from FindOpenMP.cmake while FindBLAS.cmake is doing its job.