KNF (when not conflicting with other cleanup changes in progress)
delete extra word in Nd
Don't free garbage in ec_wNAF_mul() if wNAF could be allocated but
other allocations in the same block couldn't.

problem pointed out by David Ramos on the openssl-dev list
ok miod@ doug@
correct the failure case for getentropy on win32

CryptAcquireContext and CryptGenRandom returns zero (FALSE) if fails.

From: Dongsheng Song <dongsheng.song@gmail.com>