fix a simple index bug in ff_aac_usac_reset_state()
that writes past the end of ChannelElement.ch[2] for CPE
ff_aac_usac_reset_state() loops over channels with j < ch, but
incorrectly takes &che->ch[ch]. For CPE (ch == 2) this becomes
che->ch[2], which is one past the end of ChannelElement.ch[2], and the
subsequent memset() causes an intra-object out-of-bounds write.
index the channel element with the loop variable (j).
(cherry picked from commit be82aef7cc)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>