Reapplied optimizations (150% speedup on x86_32) and other fixes,

relicensing them as LGPL.
* blowfish.c (do_encrypt): Renamed, to...
(encrypt): ...new name.
(F): Added context argument. Shift input explicitly, instead of
reading individual bytes via memory.
(R): Added context argument.
(encrypt): Deleted a bunch of local variables. Using the context
pointer for everything should consume less registers.
(decrypt): Likewise.
(initial_ctx): Arrange constants into a struct, to simplify key setup.
(blowfish_set_key): Some simplification.

Rev: nettle/ChangeLog:1.123
Rev: nettle/blowfish.c:1.5