resample: unify alloc/realloc paths in update_filter()
resample: unify alloc/realloc paths in update_filter()

The only difference between speex_alloc(size) and speex_realloc(NULL, size)
is that speex_alloc zero-initializes the memory, but every byte of memory
allocated is subsequently set anyway.

This also means that st->sinc_table_length is initialized even on the first
allocation of sinc_table.

Signed-off-by: Tristan Matthews <58557b70081517323d8b069e20d681de970f25f5@gmail.com>

ksophocleous/speexdsp,maolin-cdzl/speexdsp,felipebetancur/speexdsp,felipebetancur/speexdsp,maolin-cdzl/speexdsp,ksophocleous/speexdsp,felipebetancur/speexdsp,ksophocleous/speexdsp,maolin-cdzl/speexdsp,ksophocleous/speexdsp,felipebetancur/speexdsp,maolin-cdzl/speexdsp