Removed unused function
Micro optimization, removed some unused things.
Bignum: Fixed aliasing problem with DO_INT_TYPE_*_OVERFLOW().

Gcc 4.1.2 doesn't alias pointers to INT_TYPE and the corresponding
pointer to INT32/INT64, so stores to the target variable could get
lost in when the DO_INT_TYPE_*_OVERFLOW() functions were used in
eg loops.

Also fixes some related compiler warnings.

Fixes [bug 7057].
Fixed warning when compiling on Linux < 2.6 with gcc >= 4.9
Added LinuxThreads configure test.

HAVE_BROKEN_LINUX_THREAD_EUID is now only defined
when euid is indeed broken.
Removed some unused preprocessor macros.
SSL: Added support for some DH cipher suites.

This adds support for the DH_DSS and DH_RSA key exchange
methods, and adds the corresponding cipher suites.

Note that the only difference between the two is whether the
server certificate is signed with DSS or RSA.