Fix memory leak in para_play().

Fix memory leak in para_play().

We leak one filter parse result per audio file played. Valgrind reports:

==24559== 24 (12 direct, 12 indirect) bytes in 1 blocks are definitely lost in loss record 34 of 104
==24559==    at 0x4044B0B: calloc (vg_replace_malloc.c:1328)
==24559==    by 0x453A997: lls_parse (lopsub.c:768)
==24559==    by 0x8057612: filter_setup (filter_common.c:98)
==24559==    by 0x80500A4: load_file (play.c:377)
==24559==    by 0x80500A4: load_next_file (play.c:454)
==24559==    by 0x80500A4: play_post_monitor (play.c:1154)
==24559==    by 0x8051110: call_post_monitor (sched.c:80)
==24559==    by 0x8051110: sched_post_monitor (sched.c:106)
==24559==    by 0x8051110: schedule (sched.c:148)
==24559==    by 0x804EB80: main (play.c:1217)