Add virtio-9p (aka VirtFS) filesystem sharing to bhyve.

VirtFS allows sharing an arbitrary directory tree between bhyve virtual
machine and the host. Current implementation has a fairly complete support
for 9P2000.L protocol, except for the extended attribute support. It has
been verified to work with the qemu-kvm hypervisor.

Reviewed by:	rgrimes, emaste, jhb, trasz
Approved by:	trasz (mentor)
MFC after:	1 month
Relnotes:	yes
Sponsored by:	Conclusive Engineering (development), vStack.com (funding)
Differential Revision:	https://reviews.freebsd.org/D10335

lib/lib9p/Makefile

@@ -0,0 +1,28 @@
+# $FreeBSD$
+
+.PATH:		${.CURDIR}/../../contrib/lib9p
+CFLAGS+=	-DWITH_CASPER
+CFLAGS+=	-I${.CURDIR}
+CFLAGS+=	-I${.CURDIR}/../../contrib/lib9p
+
+LIB=		9p
+PACKAGE=	lib${LIB}
+SHLIB_MAJOR=	1
+SRCS=		connection.c \
+		genacl.c \
+		hashtable.c \
+		log.c \
+		pack.c \
+		request.c \
+		rfuncs.c \
+		threadpool.c \
+		utils.c \
+		backend/fs.c \
+		transport/socket.c
+
+INCSDIR=	${INCLUDEDIR}/lib9p
+INCS=		fid.h lib9p.h backend/fs.h
+
+LIBADD=		sbuf
+
+.include <bsd.lib.mk>