From https://github.com/xu4-engine/u4/commit/6a7ee3d0079cfdc1c8fb9ba7a3c710a957155a71
From: Karl Robillard <wickedsmoke@users.sourceforge.net>
Date: Thu, 5 Jun 2025 12:42:51 -0400
Subject: [PATCH] Makefile.common: Fix GLFW build.

--- a/src/Makefile.common
+++ b/src/Makefile.common
@@ -77,8 +77,10 @@ CXXSRCS=\
 ifeq ($(UI),glv)
 	CSRCS+=$(GLV_SRC)
 else
+ifneq ($(UI),glfw)
 	CXXSRCS+=event_$(UI).cpp
 endif
+endif
 
 #ifeq ($(CONF),boron)
 	CSRCS+=module.c support/cdi.c