Fix radeon kms compiled with clang.

[Christiano F. Haesbaert]

This will prevent xorg from segfaulting at startup if compiled with
clang, this was observed in bitrig (openbsd fork), as well as other
systems, as it can be seen here: 

https://bugs.freedesktop.org/show_bug.cgi?id=47160

This patch makes my radeon hd6770 work without problems in clang.

ps: I'm not subscribed to the list

>From c0795485027baba0b8cff90f6d30fa008265469b Mon Sep 17 00:00:00 2001
From: "Christiano F. Haesbaert" <haesbaert at haesbaert.org>
Date: Sat, 30 Nov 2013 17:33:07 +0100
Subject: [PATCH] Fix radeon kms on clang.

clang optimizations will consider this undefined behaviour due to
uninitiliazed data. Xorg was segfaulting on startup with radeonkms on
a HD6770, found out by fixing the clang warnings.
---
 src/radeon_dri2.c | 2 +-
 src/radeon_kms.c  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git src/radeon_dri2.c src/radeon_dri2.c
index 79d8f39..4498606 100644
--- src/radeon_dri2.c
+++ src/radeon_dri2.c
@@ -576,7 +576,7 @@ static void
 radeon_dri2_client_state_changed(CallbackListPtr *ClientStateCallback, pointer data, pointer calldata)
 {
     DRI2ClientEventsPtr pClientEventsPriv;
-    DRI2FrameEventPtr ref;
+    DRI2FrameEventPtr ref = NULL;
     NewClientInfoRec *clientinfo = calldata;
     ClientPtr pClient = clientinfo->client;
     pClientEventsPriv = GetDRI2ClientEvents(pClient);
diff --git src/radeon_kms.c src/radeon_kms.c
index 44a0139..223d669 100644
--- src/radeon_kms.c
+++ src/radeon_kms.c
@@ -270,7 +270,7 @@ static void
 radeon_dirty_update(ScreenPtr screen)
 {
 	RegionPtr region;
-	PixmapDirtyUpdatePtr ent;
+	PixmapDirtyUpdatePtr ent = NULL;
 
 	if (xorg_list_is_empty(&screen->pixmap_dirty_list))
 		return;
-- 
1.8.4.3