cmake HAVE_CBLAS_DGEMM examples

OSGeo/grass cmake/find_scripts/FindCBLAS.cmake :97 

check_symbol_exists(cblas_dgemm "cblas.h" HAVE_CBLAS_DGEMM)

OSGeo/grass cmake/find_scripts/FindCBLAS.cmake :103 

find_package_handle_standard_args(
  CBLAS
  REQUIRED_VARS CBLAS_FOUND CBLAS_LIBRARIES CBLAS_INCLUDEDIR HAVE_CBLAS_DGEMM
  VERSION_VAR CBLAS_VERSION)