games/thedarkmod: fix build with LLVM11

LLVM11 no longer allows assigning NULL to variables of type bool.
ok thfr@

games/thedarkmod/Makefile

@@ -1,4 +1,4 @@
-# $OpenBSD: Makefile,v 1.2 2019/09/03 16:56:43 sthen Exp $
+# $OpenBSD: Makefile,v 1.3 2021/03/12 16:39:33 naddy Exp $
 
 ONLY_FOR_ARCHS =	amd64 i386
 BROKEN-i386 =	Simd_SSE.cpp fails, unknown type name '__m128'
@@ -8,6 +8,7 @@ COMMENT =	first-person stealth game inspired by Thief
 V =		2.07
 DISTNAME =	thedarkmod.${V}
 PKGNAME =	thedarkmod-${V}
+REVISION =	0
 
 CATEGORIES =	games x11
 HOMEPAGE =	http://www.thedarkmod.com

games/thedarkmod/patches/patch-sound_snd_efxfile_cpp

@@ -0,0 +1,14 @@
+$OpenBSD: patch-sound_snd_efxfile_cpp,v 1.1 2021/03/12 16:39:33 naddy Exp $
+
+Index: sound/snd_efxfile.cpp
+--- sound/snd_efxfile.cpp.orig
++++ sound/snd_efxfile.cpp
+@@ -402,7 +402,7 @@ bool idEFXFile::LoadFile( const char *filename/*, bool
+ 	}
+ 
+ 	if ( !src.ExpectTokenString( "Version" ) ) {
+-		return NULL;
++		return false;
+ 	}
+ 
+ 	version = src.ParseInt();

games/thedarkmod/patches/patch-ui_Window_cpp

@@ -0,0 +1,14 @@
+$OpenBSD: patch-ui_Window_cpp,v 1.1 2021/03/12 16:39:33 naddy Exp $
+
+Index: ui/Window.cpp
+--- ui/Window.cpp.orig
++++ ui/Window.cpp
+@@ -2063,7 +2063,7 @@ bool idWindow::ParseRegEntry(const char *name, idParse
+ 	work = name;
+ 	work.ToLower();
+ 
+-	idWinVar *var = GetWinVarByName(work, NULL);
++	idWinVar *var = GetWinVarByName(work, false);
+ 	if ( var ) {
+ 		for (int i = 0; i < NumRegisterVars; i++) {
+ 			if (idStr::Icmp(work, RegisterVars[i].name) == 0) {