Make cinematic times be int like CL_ScaledMilliseconds

Cinematic's startTime and lastTime are always set from CL_ScaledMilliseconds
which returns int and are converted back and forth to int and unsigned int.

This fixes a warning that abs() is used on an unsigned int.

code/client/cl_cin.c

@@ -94,8 +94,8 @@ typedef struct {
 	qboolean			looping, holdAtEnd, dirty, alterGameState, silent, shader;
 	fileHandle_t		iFile;
 	e_status			status;
-	unsigned int		startTime;
-	unsigned int		lastTime;
+	int					startTime;
+	int					lastTime;
 	long				tfps;
 	long				RoQPlayed;
 	long				ROQSize;