irr: RTT flipping workaround

Didn't find the cause of this bug, but merely a workaround that only works for STK.

Still, that's two days of searching, cutting my losses.


git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@13379 178a84e3-b1eb-0310-8ba1-8eac791a3b58

lib/irrlicht/changes.stk

@@ -6,3 +6,4 @@ The following changes have been made:
 - materialtype override
 - skies respect Z
 - partial backport to expose setCurrentRendertime in the scene mgr
+- a workaround for every other RTTs flipping

lib/irrlicht/source/Irrlicht/COpenGLDriver.cpp

@@ -987,7 +987,7 @@ void COpenGLDriver::setTransform(E_TRANSFORMATION_STATE state, const core::matri
 			else
 			{
 				GLfloat glmat[16];
-				if (isRTT)
+				if (isRTT && CurrentTarget == ERT_FRAME_BUFFER)
 					getGLTextureMatrix(glmat, mat * TextureFlipMatrix);
 				else
 					getGLTextureMatrix(glmat, mat);