cmake HAVE_SYSTEM_LFS_FTS examples

Cisco-Talos/clamav cmake/CheckFTS.cmake :10

check_c_source_compiles(
    "
    #include <fts.h>

    int main(void) {
        fts_open((void *)0, FTS_PHYSICAL, (void *)0);

        return 0;
    }
    "
    HAVE_SYSTEM_LFS_FTS )