Add option to print render time of each frame to log file

Signed-off-by: Vojtech Bocek <vbocek@gmail.com>

Change-Id: Id158a6375fbadf4cdf0a8c7d143759e602419e7f
diff --git a/twrp-functions.hpp b/twrp-functions.hpp
index eb88ae2..587d772 100644
--- a/twrp-functions.hpp
+++ b/twrp-functions.hpp
@@ -60,6 +60,7 @@
 	static int copy_file(string src, string dst, int mode); //copy file from src to dst with mode permissions
 	static unsigned int Get_D_Type_From_Stat(string Path);                      // Returns a dirent dt_type value using stat instead of dirent
 	static timespec timespec_diff(timespec& start, timespec& end);	            // Return a diff for 2 times
+	static int32_t timespec_diff_ms(timespec& start, timespec& end);            // Returns diff in ms
 	static int read_file(string fn, vector<string>& results); //read from file
 	static int read_file(string fn, string& results); //read from file
 	static int write_file(string fn, string& line); //write from file