[Snowball-discuss] Patch to reduce the size of struct SN_env

[Olly Betts]

Currently "struct SN_env" stores the sizes of the 3 arrays, but we don't
actually need to know I_size or B_size to free them, and we can
trivially pass S_size to SN_close_env from the generated code:

http://oligarchy.co.uk/xapian/patches/snowball-shrink-SN_env-struct.patch

This may not apply cleanly without the previous patch to change the
type of "SN_env.B".

Cheers,
    Olly