security/ncrack: fix build on -CURRENT

This port seems to have been affected by the recent FORTIFY_SOURCE
update on -CURRENT. The error message was:

In file included from strlcpy.c:21:
In file included from ./includes.h:190:
In file included from ./entropy.h:30:
In file included from ./buffer.h:28:
In file included from ./sshbuf.h:29:
In file included from /usr/local/include/openssl/bn.h:26:
In file included from /usr/local/include/openssl/crypto.h:25:
In file included from /usr/include/stdlib.h:73:
/usr/include/ssp/stdlib.h:41:33: error: static declaration of
               '_ssh_compat_realpath' follows non-static declaration
   41 | __ssp_redirect_raw_impl(char *, realpath, realpath,
      |                                 ^
./openbsd-compat.h:98:7: note: previous declaration is here
   98 | char *realpath(const char *path, char *resolved);
      |       ^
./openbsd-compat.h:95:26: note: expanded from macro 'realpath'
   95 | #  define realpath(x, y) _ssh_compat_realpath(x, y)
      |                          ^
2 errors generated.

security/ncrack/Makefile

@@ -1,6 +1,6 @@
 PORTNAME=	ncrack
 DISTVERSION=	0.7
-PORTREVISION=	1
+PORTREVISION=	2
 CATEGORIES=	security
 
 MAINTAINER=	se@FreeBSD.org

security/ncrack/files/patch-opensshlib_openbsd-compat.h

@@ -0,0 +1,11 @@
+--- opensshlib/openbsd-compat.h.orig	2019-08-24 22:25:32 UTC
++++ opensshlib/openbsd-compat.h
+@@ -95,7 +95,7 @@ void *recallocarray(void *, size_t, size_t, size_t);
+ #  define realpath(x, y) _ssh_compat_realpath(x, y)
+ # endif
+ 
+-char *realpath(const char *path, char *resolved);
++static char *realpath(const char *path, char *resolved);
+ #endif
+ 
+ #ifndef HAVE_RRESVPORT_AF