Add support for new and old openssl API

RSA_generate_key is marked as deprecated and as been remplaced by
RSA_generate_key_ex.
Some distributors, like Android, do not support deprecated openssl.
This patch add support for RSA_generate_key_ex. If both are available,
RSA_generate_key_ex (newer) is chosen.

Conflicts:
	cf-key/cf-key.c
Move attributes' checking of files promises to cf-agent
Remove unused parameter from FuzzyHostParse
Mark unused arguments as such
Remove unused argument in MatchRegion
Only define function used in assert() if asserts are enabled
AcquireLock no longer uses EvalContext
Remove unused arguments in SelectLeaf, RegisterAHardLink
Mark unused argument as such
Remove code which will never be invoked in cf-agent due to THIS_AGENT_TYPE chech
Remove unused enum value
VerifyLink* actually returns PromiseResult, not char
De-duplicate multiple exit locations in VerifyFilePromise
Remove useless variable
Work around procfs.h refusing to compile in 32-bit LFS environment