give a chance to set USE_BLAS64 in Make.usr
use system libopenblas via set USE_SYSTEM_OPENBLAS=1
use var name LIBOPENBLAS_PATH while using system libopenblas
correct blas info in function `versioninfo'
remove USE_SYSTEM_OPENBLAS
typofix
Merge pull request #3628 from KDr2/kd/libblas

Use system provided libblas/libopenblas on Linux x64