diff -uNr libX11-1.7.0/configure libX11-1.7.0.mod/configure
--- libX11-1.7.0/configure	2020-11-20 19:08:19.000000000 +0000
+++ libX11-1.7.0.mod/configure	2020-12-07 23:41:45.588377415 +0000
@@ -19609,6 +19609,7 @@
 # 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
@@ -19654,7 +19655,7 @@
 	fi
 fi
 rm -f conftest.$ac_ext
-
+fi
 
 
 
