define aok in libnvpair which is linked to all zfs libraries that need aok

This removes the circular dependency of libnvpair on libzfs / libzpool.

PR:		199811
Obtained from:	bapt
MFC after:	23 days

cddl/contrib/opensolaris/lib/libzfs/common/libzfs_util.c

@@ -55,7 +55,6 @@
 #include "zfs_prop.h"
 #include "zfeature_common.h"
 
-int aok;
 
 int
 libzfs_errno(libzfs_handle_t *hdl)

cddl/contrib/opensolaris/lib/libzpool/common/kernel.c

@@ -45,7 +45,9 @@
  * Emulation of kernel services in userland.
  */
 
+#ifndef __FreeBSD__
 int aok;
+#endif
 uint64_t physmem;
 vnode_t *rootdir = (vnode_t *)0xabcd1234;
 char hw_serial[HW_HOSTID_LEN];

sys/cddl/contrib/opensolaris/common/nvpair/opensolaris_nvpair.c

@@ -44,6 +44,14 @@
 #endif
 #define	skip_whitespace(p)	while ((*(p) == ' ') || (*(p) == '\t')) p++
 
+#if defined(__FreeBSD__) && !defined(_KERNEL)
+/*
+ * libnvpair is the lowest commen denominator for ZFS related libraries,
+ * defining aok here makes it usable by all ZFS related libraries
+ */
+int aok;
+#endif
+
 /*
  * nvpair.c - Provides kernel & userland interfaces for manipulating
  *	name-value pairs.