Also, document why CTR IV size is now set to 16, so user is noted to set
IV appropriately to full extent (including counter). Basically, it's for
openssh (and alike) to make it copy IV from privilege separated process.

(cherry picked from commit 74d13288)

Previous implementation was not OFB at all, and fail tests.

Note: This implementation is for fixed width 128-bit IV which makes
shift regiser redundant.

(cherry picked from commit 1e15537d)

Previously CTR did not continue unfinished block on the next cipher
iteration.

(cherry picked from commit cf2ab51a)

(cherry picked from commit 6be1ab00)

Address compiler warnings and build with CMAKE_C_FLAGS

like the README suggests.

Fix error in printf() invocation

where they reside

Make gost-engine independent of OpenSSL SOURCE

It really already was, this only removes artifacts in CMakeLists.txt

Separate GOST engine and GOST library, make GOST engine a module

The GOST engine file was "libgost_engine.so".  Unfortunately, this
will fail to load with any OpenSSL version, as the derived engine ID
will be "gost_engine" (OpenSSL <1.1.0) or "libgost_engine" (OpenSSL
>=1.1.0), since the engine checks the ID internally against "gost".

To make the IDs compatible, make sure the file name will be "gost.so"

The GOST engine is a dynamically loadable module rather than a shared
library, so make that explicit.  However, the programs gost12sum,
gostsum and gostsum12 need to link against the algorithms implemented
as part of the engine, so separate those out into a static library
that both programs and engine link with.

Conflicts:
	gost_asn1.c
	gost_crypt.c