This fixes the following compilation error.

-----
  CC       demux/libts_plugin_la-ts.lo
demux/ts.c: In function 'EITCallBack':
demux/ts.c:3114:13: error: implicit declaration of function 'time' [-Werror=implicit-function-declaration]
             time_t timer = time( NULL );
             ^
demux/ts.c:3115:13: error: implicit declaration of function 'difftime' [-Werror=implicit-function-declaration]
             int64_t diff = difftime( mktime( localtime( &timer ) ),
             ^
demux/ts.c:3115:13: error: implicit declaration of function 'mktime' [-Werror=implicit-function-declaration]
demux/ts.c:3115:13: error: implicit declaration of function 'localtime' [-Werror=implicit-function-declaration]
demux/ts.c:3116:38: error: implicit declaration of function 'gmtime' [-Werror=implicit-function-declaration]
                                      mktime( gmtime( &timer ) ) );
                                      ^
-----
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>