graphics/mesa-dri: Fix a crash for radeon r600 graphic cards.

Add an upstream patch to fix an immediate crash of Xorg and wayland
on systems with radeon r600 based graphic cards. See:

https://gitlab.freedesktop.org/mesa/mesa/-/issues/7931

PR: 268327

graphics/mesa-dri/Makefile

@@ -1,5 +1,6 @@
 PORTNAME=	mesa-dri
 PORTVERSION=	${MESAVERSION}
+PORTREVISION=	1
 CATEGORIES=	graphics
 
 COMMENT=	OpenGL hardware acceleration drivers for DRI2+

graphics/mesa-dri/files/patch-src_gallium_drivers_r600_sfn_sfn__optimizer.cpp

@@ -0,0 +1,16 @@
+--- src/gallium/drivers/r600/sfn/sfn_optimizer.cpp.orig	2022-12-14 21:06:11 UTC
++++ src/gallium/drivers/r600/sfn/sfn_optimizer.cpp
+@@ -354,7 +354,12 @@ CopyPropFwdVisitor::visit(AluInstr *instr)
+    auto src = instr->psrc(0);
+    auto dest = instr->dest();
+ 
+-   for (auto& i : dest->uses()) {
++   auto ii = dest->uses().begin();
++   auto ie = dest->uses().end();
++
++   while(ii != ie) {
++      auto i = *ii;
++      ++ii;
+       /* SSA can always be propagated, registers only in the same block
+        * and only if they are assigned in the same block */
+       bool can_propagate = dest->is_ssa();