fix for EXT-8730: crash at llrender/llimagegl.cpp(157) : error ERROR:...

fix for EXT-8730: crash at llrender/llimagegl.cpp(157) : error ERROR: checkTexSize: wrong texture size and discard level: width: 512 Height: 512 Current Level:

indra/newview/lldynamictexture.cpp

@@ -167,10 +167,14 @@ void LLViewerDynamicTexture::postRender(BOOL success)
 			{
 				generateGLTexture() ;
 			}
-			if(!mGLTexturep->getHasGLTexture())
+			else if(!mGLTexturep->getHasGLTexture())
 			{
 				generateGLTexture() ;
 			}			
+			else if(mGLTexturep->getDiscardLevel() != 0)//do not know how it happens, but regenerate one if it does.
+			{
+				generateGLTexture() ;
+			}
 
 			if(gGLManager.mDebugGPU)
 			{