text-freetype2: Set font log warning to debug only

plugins/text-freetype2/find-font-iconv.c

@@ -139,7 +139,7 @@ char *sfnt_name_to_utf8(FT_SfntName *sfnt_name)
 
 	iconv_t ic = iconv_open("UTF-8", charset);
 	if (ic == (iconv_t)-1) {
-		blog(LOG_WARNING, "couldn't intialize font code page "
+		blog(LOG_DEBUG, "couldn't intialize font code page "
 				  "conversion:  '%s' to 'utf-8': errno = %d",
 				  charset, (int)errno);
 		return NULL;