cmake HAS_UNDERSCORE examples

jlblancoc/suitesparse-metis-for-windows SuiteSparse/SuiteSparse_config/cmake_modules/SuiteSparseBLAS64.cmake :41 

string ( FIND ${BLAS64_SUFFIX} "_" HAS_UNDERSCORE )

DrTimothyAldenDavis/SuiteSparse SuiteSparse_config/cmake_modules/SuiteSparseBLAS64.cmake :43 

string ( FIND ${BLAS64_SUFFIX} "_" HAS_UNDERSCORE )