Print debug timestamps to same stream as rest of output

We used fprintf() elsewhere in this function, but we didn't use it on
the debug timestamp printing. Use fprintf() instead of printf() to fix
this.

Signed-off-by: Dan McGee <dan@archlinux.org>

src/pacman/util.c

@@ -1416,7 +1416,7 @@ int pm_vfprintf(FILE *stream, alpm_loglevel_t level, const char *format, va_list
 		strftime(timestr, 9, "%H:%M:%S", tmp);
 		timestr[8] = '\0';
 
-		printf("[%s] ", timestr);
+		fprintf(stream, "[%s] ", timestr);
 	}
 #endif