rv790, d-r-t, git ddx,mesa,libdrm and xserver 1.9

ut2004 demo segfaults for me since -

commit ac8a1ebe55b08180945ffaebcff6b3bed336c9ec
Author: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Date:   Tue Oct 5 21:01:43 2010 +0200

    r600g: use dirty list to track dirty blocks
    
    Got a speed up by tracking the dirty blocks in a seperate list instead of looping through all blocks. This version should work with block that get their dirty state disabled again and I added a dirty check during the flush as some blocks were already dirty.

Log: [ 1]  ./ut2004-bin [0x85a5921]
Log: [ 2]  [0xffffe400]
Log: [ 3]  /home/andy/Src/Mesa-git/mesa/lib/gallium/r600_dri.so [0xb40d31a1]
Log: [ 4]  /home/andy/Src/Mesa-git/mesa/lib/gallium/r600_dri.so [0xb40b20e1]
Log: [ 5]  /home/andy/Src/Mesa-git/mesa/lib/gallium/r600_dri.so [0xb42565cd]
Log: [ 6]  /home/andy/Src/Mesa-git/mesa/lib/gallium/r600_dri.so [0xb42342aa]
Log: [ 7]  /home/andy/Src/Mesa-git/mesa/lib/gallium/r600_dri.so [0xb4231539]
Log: [ 8]  /home/andy/Src/Mesa-git/mesa/lib/gallium/r600_dri.so [0xb42047be]
Log: [ 9]  /home/andy/Src/Mesa-git/mesa/lib/gallium/r600_dri.so [0xb4228cfe]
Log: [10]  /home/andy/Src/Mesa-git/mesa/lib/gallium/r600_dri.so [0xb422936a]
Log: [11]  /home/andy/Src/Mesa-git/mesa/lib/gallium/r600_dri.so [0xb4185585]
Log: [12]  ./ut2004-bin(_ZN22FOpenGLRenderInterface13DrawPrimitiveE14EPrimitiveTypeiiii+0x2dd) [0x87089cd]
Log: [13]  ./ut2004-bin(_Z11DrawSectionP11UStaticMeshiP9UMaterialP16FRenderInterface+0xbf) [0x834b77f]
Log: [14]  ./ut2004-bin(_Z16RenderStaticMeshP13FDynamicActorP15FLevelSceneNodeP5TListIP13FDynamicLightEPS3_IP20FProjectorRenderInfoEP16FRenderInterface+0x14f4) [0x834d5c4]
Log: [15]  ./ut2004-bin(_ZN13FDynamicActor6RenderEP15FLevelSceneNodeP5TListIP13FDynamicLightEPS2_IP20FProjectorRenderInfoEP16FRenderInterface+0x22eb) [0x83134cb]
Log: [16]  ./ut2004-bin [0x83378ec]
Log: [17]  ./ut2004-bin(_Z11RenderLevelP15FLevelSceneNodeP16FRenderInterface+0xed2) [0x8334212]
Log: [18]  ./ut2004-bin(_ZN15FLevelSceneNode6RenderEP16FRenderInterface+0x66c) [0x831b52c]
Log: [19]  ./ut2004-bin(_Z11RenderLevelP15FLevelSceneNodeP16FRenderInterface+0xc79) [0x8333fb9]
Log: [20]  ./ut2004-bin(_ZN15FLevelSceneNode6RenderEP16FRenderInterface+0x66c) [0x831b52c]
Log: [21]  ./ut2004-bin(_Z11RenderLevelP15FLevelSceneNodeP16FRenderInterface+0xc79) [0x8333fb9]
Log: [22]  ./ut2004-bin(_ZN15FLevelSceneNode6RenderEP16FRenderInterface+0x66c) [0x831b52c]
Log: [23]  ./ut2004-bin(_Z11RenderLevelP15FLevelSceneNodeP16FRenderInterface+0xc79) [0x8333fb9]
Log: [24]  ./ut2004-bin(_ZN15FLevelSceneNode6RenderEP16FRenderInterface+0x66c) [0x831b52c]
Log: [25]  ./ut2004-bin(_ZN16FPlayerSceneNode6RenderEP16FRenderInterface+0x1da) [0x831f8ba]
Log: [26]  ./ut2004-bin(_ZN11UGameEngine4DrawEP9UViewportiPhPi+0x6c4) [0x8240f04]
Log: [27]  ./ut2004-bin(_ZN12USDLViewport7RepaintEi+0x56) [0x86f8136]
Log: [28]  ./ut2004-bin(_ZN10USDLClient4TickEv+0x159) [0x86f6359]
Log: [29]  ./ut2004-bin(_ZN11UGameEngine4TickEf+0x517) [0x82459b7]
Log: [30]  ./ut2004-bin(_ZN9CMainLoop7RunLoopEv+0x108) [0x815a7a8]
Log: [31]  ./ut2004-bin [0x81521cf]
Log: [32]  ./ut2004-bin(main+0x2c8f) [0x814e1df]
Log: [33]  /lib/libc.so.6(__libc_start_main+0xd0) [0xb74f7380]
Log: [34]  ./ut2004-bin(readdir+0x95) [0x814b321]