cmake HAVE_ISNAND examples

SCIInstitute/SCIRun src/Externals/libxml2/CMakeLists.txt :142 

CHECK_FUNCTION_EXISTS("isnand" HAVE_ISNAND)

GenericMappingTools/gmt cmake/modules/ConfigureChecks.cmake :369 

check_symbol_exists (isnand      "${_math_h}" HAVE_ISNAND)