libfdt: Make an internal FDT library available

This will be used by bhyve to build a device tree when booting arm64
guests.

Reviewed by:	corvink, jhb
MFC after:	1 week
Sponsored by:	Innovate UK
Differential Revision:	https://reviews.freebsd.org/D40994

lib/Makefile

@@ -171,6 +171,7 @@ SUBDIR+=	clang
 SUBDIR.${MK_CUSE}+= 	libcuse
 SUBDIR.${MK_TOOLCHAIN}+=libpe
 SUBDIR.${MK_DIALOG}+=	libdpv libfigpar
+SUBDIR.${MK_FDT}+=	libfdt
 SUBDIR.${MK_FILE}+=	libmagic
 SUBDIR.${MK_GPIO}+=	libgpio
 SUBDIR.${MK_GSSAPI}+=	libgssapi librpcsec_gss

lib/libfdt/Makefile

@@ -0,0 +1,29 @@
+LIB=		fdt
+
+INTERNALLIB=
+
+LIBFDTSRCDIR=	${SRCTOP}/sys/contrib/libfdt
+.PATH:		${LIBFDTSRCDIR}
+
+SRCS=					\
+		fdt.c			\
+		fdt_addresses.c		\
+		fdt_empty_tree.c	\
+		fdt_overlay.c		\
+		fdt_ro.c		\
+		fdt_rw.c		\
+		fdt_strerror.c		\
+		fdt_sw.c		\
+		fdt_wip.c
+
+INCS=					\
+		fdt.h			\
+		libfdt.h		\
+		ibfdt_env.h
+
+CFLAGS+=	-I${LIBFDTSRCDIR}
+WARNS?=		2
+
+MAN=
+
+.include <bsd.lib.mk>

share/mk/src.libnames.mk

@@ -44,6 +44,7 @@ _INTERNALLIBS=	\
 		c_nossp_pic \
 		cron \
 		elftc \
+		fdt \
 		fifolog \
 		ifconfig \
 		ipf \
@@ -546,6 +547,9 @@ _LIB_OBJTOP?=	${OBJTOP}
 LIBELFTCDIR=	${_LIB_OBJTOP}/lib/libelftc
 LIBELFTC?=	${LIBELFTCDIR}/libelftc${PIE_SUFFIX}.a
 
+LIBFDTDIR=	${_LIB_OBJTOP}/lib/libfdt
+LIBFDT?=	${LIBFDTDIR}/libfdt${PIE_SUFFIX}.a
+
 LIBLUADIR=	${_LIB_OBJTOP}/lib/liblua
 LIBLUA?=	${LIBLUADIR}/liblua${PIE_SUFFIX}.a