* cipher/cipher-selftest.c (_gcry_selftest_helper_cbc)
(_gcry_selftest_helper_cfb, _gcry_selftest_helper_ctr): Mark variable
as unused.
* random/rndw32.c (slow_gatherer): Avoid signed pointer mismatch
warning.
* src/secmem.c (init_pool): Avoid unused variable warning.
* tests/random.c (writen, readn): Include on if needed.