Handle abnormal exit of s_client/s_server processes.

Fixes partially #230.

Support of pkeyutl -pkeyopt ukmhex:0102030405060708 syntax

There need to be more tests than 2 constant fixed size blocks.
Final digest values are generated from the first run.

Test description in comments.

Plus some minor chnages
- function defenition doen't match function declaration
- Consecutive break statement is unnecessary.
- Type missmatch in format string

Only stack buffers are considered.

`RAND_priv_bytes' is supposed to be used for private data.

OpenSSL suggests to use (and internally itself uses)
`BN_{CTX_,}secure_new' primitives to work with private keys.

These are using `OPENSSL_secure_malloc' et al. calls, which use
special 'secure heap' memory.

Along, optimize out `hashsum2bn' with `BN_lebin2bn'.

`Test2::V0' is non standard and rarely present on systems, making `make
test' unnecessarily fail.

lcc emulates x86_64 SIMD intrinsics, so SSE2 code will work as is. Even
though in benchmarks it is slightly slower than regular implementation

This is lcc bug. Curiously, it is not triggered in `test_context.c' and
`test_grasshopper.c'.

"lcc: "/usr/src/gost-engine/test_curves.c", строка 32: ошибка:
          вероятное использование "=" вместо "=="
          [-Werror=assign-where-compare-meant]
  #define TEST_ASSERT(e) {if ((test = (e))) \
                              ^
 в раскрытие макроса "TEST_ASSERT" на строке 217
      TEST_ASSERT(0);"