cmake HAVE_CEILF examples

llvm-dcpu16/llvm-dcpu16 cmake/config-ix.cmake :105 

check_symbol_exists(ceilf math.h HAVE_CEILF)

KhronosGroup/SPIRV-LLVM cmake/config-ix.cmake :142 

check_symbol_exists(ceilf math.h HAVE_CEILF)