These are default options defined inside isc.cf. You can redefine them inside host.def.
Here is a sample host.def (the one I use for XFree86 4.0):
/* Disable the use of /var/X11 and /etc/X11 */ #define HasVarDirectory NO #define UseEtcX11 NO /* Use inline Math from linux ;-) package inline-math-2.6.tar.gz */ /* should be available on your favorite linux ftp */ # define UseInlineMath YES /* Use cbrt from liboptm.a (Interactive icc Compiler) */ # define HasCbrt YES /* Use GNUs MallocLibrary (and the Location for the Lib) */ # define UseGnuMalloc YES /* Expand Manual Pages (needs S5L) */ # define ExpandManNames YES /* if you have groff or the TextProcessingWorkbench - don't preformat*/ # define FormattedManPages NO /* XF86Setup Util */ # define HasTk YES # define HasTcl YES /* use doctools */ # define HasSgmlFmt YES # define BuildAllDocs YES # define BuildLinuxDocText NO # define BuildLinuxDocPS NO #define GlxBuiltInMesa YES