This change will cause builds (by default) to not use different STACK

structures and functions for each stack type. The previous behaviour
can be enabled by configuring with the "-DDEBUG_SAFESTACK" option.
This will also cause "make update" (mkdef.pl in particular) to
update the libeay.num and ssleay.num symbol tables with the number of
extra functions DEBUG_SAFESTACK creates.

The way this change works is to accompany each DECLARE_STACK_OF()
macro with a set of "#define"d versions of the sk_##type##_***
functions that ensures all the existing "type-safe" stack calls are
precompiled into the underlying stack calls. The presence or abscence
of the DEBUG_SAFESTACK symbol controls whether this block of
"#define"s or the DECLARE_STACK_OF() macro is taking effect. The
block of "#define"s is in turn generated and maintained by a perl
script (util/mkstack.pl) that encompasses the block with delimiting
C comments. This works in a similar way to the auto-generated error
codes and, like the other such maintenance utilities, is invoked
by the "make update" target.

A long (but mundane) commit will follow this with the results of
"make update" - this will include all the "#define" blocks for
each DECLARE_STACK_OF() statement, along with stripped down
libeay.num and ssleay.num files.