diff -uNr xorg-server-1.20.10/configure xorg-server-1.20.10.mod/configure
--- xorg-server-1.20.10/configure	2020-12-01 16:32:41.000000000 +0000
+++ xorg-server-1.20.10.mod/configure	2020-12-08 20:24:46.708451366 +0000
@@ -21814,6 +21814,7 @@
 # Check for flag to avoid builtin definitions - assumes unix is predefined,
 # which is not the best choice for supporting other OS'es, but covers most
 # of the ones we need for now.
+if false; then
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking if $RAWCPP requires -undef" >&5
 $as_echo_n "checking if $RAWCPP requires -undef... " >&6; }
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -21859,7 +21860,7 @@
 	fi
 fi
 rm -f conftest.$ac_ext
-
+fi