Disable flang (over-)optimizations in BLAS tests (#3600)
Disable flang (over-)optimizations in BLAS tests (#3600)

* limit flang optimizations to -O2
xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS,xianyi/OpenBLAS