First attempt at a cryptographic mpz object.
Fixup
Moved PIKE_MODULE_EXIT to last. Made a macro for Pike_fp->current_object.
SSL: Added some constants from the TLS 1.3 draft.
Added support for buffers to Crypto.X.hash()

It now support the various buffer objects as the data source argument.
pgsql: Use close callback to reliably react to remote closes.
Eliminated a lot of Pike_fp. Saves a few percent of binary size. Should be somewhat faster too.
Configure: fixed test for __attribute__ support

va_start and other macros expect the va_list as first argument.
This test only produced warnings with most compilers, which is
why this problem was never fixed.