The goals:
1) calls from inside libcrypto to other libcrypto functions should
   be via identifiers that are of hidden visibility and -- to avoid
   confusion or conflicts -- are in the reserved namespace.  By
   doing this these calls are protected from being overridden by
   applications and on many platforms can avoid creation or use of
   GOT or PLT  entries.  I've chosen a prefix of "_lcry_" for this.
   Note that these symbols aren't in the dynamic symbol table of the
   libcrypto.so shared library...but they are visible in the static
   library.

2) calls from libssl to symbols in libcrypto should be via identifiers
   which won't be accidentally overridden by the application, libc,
   other random crypto libraries that are pulled in, etc.  I've
   chosen a prefix of "_libre_" for this.

These will not be declared directly; instead, the gcc "asm labels"
extension will be used rename the function.  In order to actually
set up the desired asm labels, we use these in the internal .h
files:

   LCRYPTO_USED(x)	Symbols used both internally and externally
	In builds of libcrypto, this makes gcc convert use of x to
	use _libre_x instead.  In other builds that use these headers,
	it makes gcc convert use of x to use _libre_x instead.  Use
	LCRYPTO_ALIAS(x) to create the external aliases.
	ex: LCRYPTO_USED(SSL_get_verify_mode)

   LCRYPTO_UNUSED(x)	Symbols that are not used internally or by libssl
	No renaming is done.  In builds of libcrypto, the symbol
	is marked as deprecated to detect unintentional use of such
	a symbol, so that it can be marked as used going forward.
	ex: LCRYPTO_UNUSED(SSL_CIPHER_get_name)

Finally, to create the expected aliases, we use these in the .c files
where the definitions are:
   LCRYPTO_ALIAS(x)
	This defines both x and _libre_x as strong aliases for _lcry_x.
	Match uses of this with uses of LCRYPTO_USED()
	ex: LCRYPTO_ALIAS(SSL_get_verify_mode)