gsdx tc: log unsupported LookupDepthSource

plugins/GSdx/GSTextureCache.cpp

@@ -87,7 +87,10 @@ void GSTextureCache::RemoveAll()
 
 GSTextureCache::Source* GSTextureCache::LookupDepthSource(const GIFRegTEX0& TEX0, const GIFRegTEXA& TEXA, const GSVector4i& r, bool palette)
 {
-	if (!CanConvertDepth()) throw GSDXRecoverableError();
+	if (!CanConvertDepth()) {
+		GL_CACHE("LookupDepthSource not supported (0x%x, F:0x%x)", TEX0.TBP0, TEX0.PSM);
+		throw GSDXRecoverableError();
+	}
 
 	const GSLocalMemory::psm_t& psm_s = GSLocalMemory::m_psm[TEX0.PSM];