Configure: add ios64 target.

Reviewed-by: Steve Marquess <marquess@openssl.org>
ecp_nistz256 update.

Facilitate switch to custom scatter-gather routines. This modification
does not change algorithms, only makes it possible to implement
alternative. This is achieved by a) moving precompute table to assembly
(perlasm parses ecp_nistz256_table.c and is free to rearrange data to
match gathering algorithm); b) adhering to explicit scatter subroutine
(which for now is simply a memcpy). First implementations that will use
this option are 32-bit assembly implementations, ARMv4 and x86, where
equivalent of current read-whole-table-select-single-value algorithm
is too time-consuming. [On side note, switching to scatter-gather on
x86_64 would allow to improve server-side ECDSA performance by ~5%].

Reviewed-by: Bodo Moeller <bodo@openssl.org>
Process signature algorithms in ClientHello late.

Reviewed-by: Tim Hudson <tjh@openssl.org>
Copy negotiated parameters in SSL_set_SSL_CTX.

SSL_set_SSL_CTX is used to change the SSL_CTX for SNI, keep the
supported signature algorithms and raw cipherlist.
Reviewed-by: Tim Hudson <tjh@openssl.org>