- Only check for HAVE_CLOCK_GETTIME and HAVE_FUTIMENS on Linux, since they are only used to implement a Linux-specific workaround related to mtime precision. - Make sure that hack is limited to Linux builds - HAVE_SYS_SYSCTL_H was unused, but we should have been using it - HAVE_TERMIOS_H was unused, remove it The only functional change is that unix machines with clock_gettime and futimens will not bother with a Linux-specific hack, and won't waste time checking for either during cmake configuration either.