SH-2276 Force RenderMaxTextureIndex to be <= 16 regardless of settings

indra/newview/llviewershadermgr.cpp

@@ -357,6 +357,9 @@ void LLViewerShaderMgr::setShaders()
 
 	LLGLSLShader::sIndexedTextureChannels = llmax(llmin(gGLManager.mNumTextureImageUnits, (S32) gSavedSettings.getU32("RenderMaxTextureIndex")), 1);
 
+	//NEVER use more than 16 texture channels (work around for prevalent driver bug)
+	LLGLSLShader::sIndexedTextureChannels = llmin(LLGLSLShader::sIndexedTextureChannels, 16);
+
 	reentrance = true;
 
 	if (LLRender::sGLCoreProfile || gGLManager.mGLVersion >= 2.f)

indra/newview/llvovolume.cpp

@@ -4666,6 +4666,8 @@ void LLVolumeGeometryManager::genDrawInfo(LLSpatialGroup* group, U32 mask, std::
 
 	texture_index_channels = llmin(texture_index_channels, (S32) gSavedSettings.getU32("RenderMaxTextureIndex"));
 	
+	//NEVER use more than 16 texture index channels (workaround for prevalent driver bug)
+	texture_index_channels = llmin(texture_index_channels, 16);
 
 	while (face_iter != faces.end())
 	{