Fix compilation on gcc systems
Fix compilation on gcc systems

lmctv/pynacl,alex/pynacl,scholarly/pynacl,JackWink/pynacl,dstufft/pynacl,xueyumusic/pynacl,Insoleet/cutecoin,dstufft/pynacl,lmctv/pynacl,lmctv/pynacl,ucoin-io/cutecoin,scholarly/pynacl,lmctv/pynacl,xueyumusic/pynacl,ucoin-io/cutecoin,pyca/pynacl,pyca/pynacl,hoffmabc/pynacl,reaperhulk/pynacl,reaperhulk/pynacl,alex/pynacl,pyca/pynacl,JackWink/pynacl,xueyumusic/pynacl,pyca/pynacl,ucoin-io/cutecoin,JackWink/pynacl,reaperhulk/pynacl,reaperhulk/pynacl,xueyumusic/pynacl,alex/pynacl,scholarly/pynacl,dstufft/pynacl,lmctv/pynacl,ucoin-bot/cutecoin,alex/pynacl,hoffmabc/pynacl,pyca/pynacl,scholarly/pynacl,JackWink/pynacl,hoffmabc/pynacl,reaperhulk/pynacl,dstufft/pynacl