cmake HAVE_SYS_DL_H examples

llvm-dcpu16/llvm-dcpu16 cmake/config-ix.cmake :65 

check_include_file(sys/dl.h HAVE_SYS_DL_H)

Cisco-Talos/clamav CMakeLists.txt :620 

check_include_file("sys/dl.h"           HAVE_SYS_DL_H)