EXA: Don't attempt to move in pixmaps that can't be accelerated.

From: Michel Dänzer <michel@tungstengraphics.com>

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=12815 .
---

 exa/exa_migration.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/exa/exa_migration.c b/exa/exa_migration.c
index 70d8e12..ff81041 100644
--- a/exa/exa_migration.c
+++ b/exa/exa_migration.c
@@ -319,6 +319,10 @@ exaMoveInPixmap (PixmapPtr pPixmap)
     if (pPixmap->drawable.bitsPerPixel < 8)
 	return;
 
+    if (pPixmap->drawable.width > pExaScr->info->maxX ||
+	pPixmap->drawable.height > pExaScr->info->maxY)
+	return;
+
     if (pExaPixmap->area == NULL) {
 	pExaPixmap->area =
 	    exaOffscreenAlloc (pScreen, pExaPixmap->fb_size,