[dx83] Restore backbuf

[Jason Edmeades <us@the-edmeades.demon.co.uk>]

When updating the back buffer directly, on unlock we have to draw it 
back to the screen. However, due to GL having a different y coordinate 
system to directx, we need it upside down. (Note this call doesnt work 
for glReadPixels (unfortunately) which is why the lock code has to read 
line by line but the unlock can draw it all back in one go).

Changelog

Make unlock of the backbuffer correctly restore the contents.

Jason
diff -u3 dlls/d3d8/dx82/surface.c dlls/d3d8/surface.c
--- dlls/d3d8/dx82/surface.c	2003-09-19 20:51:46.000000000 +0100
+++ dlls/d3d8/surface.c	2003-09-27 16:29:33.000000000 +0100
@@ -321,6 +321,8 @@
 	vcheckGLcall("glIntegerv");
 	glGetIntegerv(GL_CURRENT_RASTER_POSITION, &prev_rasterpos[0]);
 	vcheckGLcall("glIntegerv");
+        glPixelZoom(1.0, -1.0);
+        vcheckGLcall("glPixelZoom");
 
 	if (This == This->Device->backBuffer) {
 	  glDrawBuffer(GL_BACK);
@@ -361,6 +363,8 @@
 	  FIXME("Unsupported Format %u in locking func\n", This->myDesc.Format);
 	}
 
+        glPixelZoom(1.0,1.0);
+        vcheckGLcall("glPixelZoom");
 	glDrawBuffer(prev_draw);
 	vcheckGLcall("glDrawBuffer");
 	glRasterPos3iv(&prev_rasterpos[0]);