BUG/MINOR: Fix OSX compilation errors

SOL_IPV6 is not defined on OSX, breaking the compile. Also libcrypt is
not available for installation neither in Macports nor as a Brew recipe,
so we're disabling implicit dependancy.

Signed-off-by: Dinko Korunic <dinko.korunic@gmail.com>
diff --git a/Makefile b/Makefile
index 4d6ab1a..0ce4b32 100644
--- a/Makefile
+++ b/Makefile
@@ -307,7 +307,6 @@
   USE_POLL       = implicit
   USE_KQUEUE     = implicit
   USE_TPROXY     = implicit
-  USE_LIBCRYPT   = implicit
 else
 ifeq ($(TARGET),openbsd)
   # This is for OpenBSD >= 3.0
diff --git a/src/proto_tcp.c b/src/proto_tcp.c
index 9c5ea98..b614e6b 100644
--- a/src/proto_tcp.c
+++ b/src/proto_tcp.c
@@ -205,7 +205,7 @@
 	case AF_INET6:
 		if (flags && ip6_transp_working) {
 			if (0
-#if defined(IPV6_TRANSPARENT)
+#if defined(IPV6_TRANSPARENT) && defined(SOL_IPV6)
 			    || (setsockopt(fd, SOL_IPV6, IPV6_TRANSPARENT, &one, sizeof(one)) == 0)
 #endif
 #if defined(IP_FREEBIND)
@@ -853,7 +853,7 @@
 		break;
 		case AF_INET6:
 			if (1
-#if defined(IPV6_TRANSPARENT)
+#if defined(IPV6_TRANSPARENT) && defined(SOL_IPV6)
 			    && (setsockopt(fd, SOL_IPV6, IPV6_TRANSPARENT, &one, sizeof(one)) == -1)
 #endif
 #if defined(IP_FREEBIND)