Issue #28444: Fix missing extensions modules when cross compiling.
diff --git a/Makefile.pre.in b/Makefile.pre.in
index b379ce9..ba633da 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -20,6 +20,7 @@
 
 # === Variables set by makesetup ===
 
+MODNAMES=       _MODNAMES_
 MODOBJS=        _MODOBJS_
 MODLIBS=        _MODLIBS_