Remove LOADER_ZFS_SUPPORT as a Makefile variable

LOADER_ZFS_SUPPORT is entirely used to select whether or not to
support ZFS in the loader. But it's not a user-servicable part (MK_ZFS
is what's used for that) Change it to the more conventional HAVE_ZFS
and move the ZFS support code into loader.mk. In addition, only build
ZFS libraries and boot loaders when ZFS is enabled.

Sponsored by: Netflix

sys/boot/Makefile.amd64

@@ -1,7 +1,9 @@
 # $FreeBSD$
 
 SUBDIR+=		libsa32
+.if ${MK_ZFS} != "no"
 SUBDIR+=		zfs zfs32
+.endif
 .if ${MK_FORTH} != "no"
 SUBDIR+=		ficl32
 .endif

sys/boot/Makefile.i386

@@ -3,6 +3,8 @@
 .if ${LOADER_GELI_SUPPORT:Uyes} == "yes"
 SUBDIR+=		geli
 .endif
+.if ${MK_ZFS} != "no"
 SUBDIR+=		zfs
+.endif
 
 SUBDIR+=		efi

sys/boot/Makefile.sparc64

@@ -1,4 +1,6 @@
 # $FreeBSD$
 
 SUBDIR+=		ofw
+.if ${MK_ZFS} != "no"
 SUBDIR+=		zfs
+.endif

sys/boot/i386/loader/Makefile

@@ -21,6 +21,8 @@ INTERNALPROG=
 NEWVERSWHAT?=	"bootstrap loader" x86
 VERSION_FILE=	${.CURDIR}/../loader/version
 
+.PATH:		${BOOTSRC}/i386/loader
+
 # architecture-specific loader code
 SRCS=		main.c conf.c vers.c chain.c
 
@@ -30,16 +32,6 @@ CFLAGS+=	-DLOADER_FIREWIRE_SUPPORT
 LIBFIREWIRE=	${BOOTOBJ}/i386/libfirewire/libfirewire.a
 .endif
 
-# Set by zfsloader Makefile
-.if defined(LOADER_ZFS_SUPPORT)
-CFLAGS+=	-DLOADER_ZFS_SUPPORT
-.if ${MACHINE} == "amd64"
-LIBZFSBOOT=	${BOOTOBJ}/zfs32/libzfsboot.a
-.else
-LIBZFSBOOT=	${BOOTOBJ}/zfs/libzfsboot.a
-.endif
-.endif
-
 # Include bcache code.
 HAVE_BCACHE=	yes
 

sys/boot/i386/zfsloader/Makefile

@@ -1,15 +1,10 @@
 # $FreeBSD$
 
-LOADER_ZFS_SUPPORT=yes
-
-.include <bsd.init.mk>
-
-.PATH:	${BOOTSRC}/i386/loader
-
 LOADER=		zfsloader
 NEWVERSWHAT=	"ZFS enabled bootstrap loader" x86
 LOADER_ONLY=	yes
-MAN=
+HAVE_ZFS=	yes
 
+.include <bsd.init.mk>
 .include "${BOOTSRC}/i386/loader/Makefile"
 

sys/boot/loader.mk

@@ -69,6 +69,19 @@ CFLAGS+=	-DBOOT_PROMPT_123
 SRCS+=	install.c
 .endif
 
+.if defined(HAVE_ZFS)
+CFLAGS+=	-DLOADER_ZFS_SUPPORT
+CFLAGS+=	-I${ZFSSRC}
+CFLAGS+=	-I${SYSDIR}/cddl/boot/zfs
+.if ${MACHINE} == "amd64"
+# Have to override to use 32-bit version of zfs library...
+# kinda lame to select that there XXX
+LIBZFSBOOT=	${BOOTOBJ}/zfs32/libzfsboot.a
+.else
+LIBZFSBOOT=	${BOOTOBJ}/zfs/libzfsboot.a
+.endif
+.endif
+
 CLEANFILES+=	vers.c
 VERSION_FILE?=	${.CURDIR}/version
 .if ${MK_REPRODUCIBLE_BUILD} != no

sys/boot/sparc64/Makefile

@@ -1,5 +1,10 @@
 # $FreeBSD$
 
-SUBDIR=	boot1 loader zfsboot zfsloader
+.include <bsd.init.mk>
+
+SUBDIR=	boot1 loader
+.if ${MK_ZFS} != "no"
+SUBDIR+=zfsboot zfsloader
+.endif
 
 .include <bsd.subdir.mk>

sys/boot/sparc64/loader/Makefile

@@ -5,7 +5,6 @@ LOADER_UFS_SUPPORT?=	yes
 LOADER_CD9660_SUPPORT?=	yes
 LOADER_EXT2FS_SUPPORT?=	no
 LOADER_MSDOS_SUPPORT?=	no
-LOADER_ZFS_SUPPORT?=	no
 LOADER_NET_SUPPORT?=	yes
 LOADER_NFS_SUPPORT?=	yes
 LOADER_TFTP_SUPPORT?=	yes
@@ -28,12 +27,6 @@ SRCS=		locore.S main.c metadata.c vers.c
 .if ${LOADER_DEBUG} == "yes"
 CFLAGS+=	-DLOADER_DEBUG
 .endif
-.if ${LOADER_ZFS_SUPPORT} == "yes"
-CFLAGS+=	-DLOADER_ZFS_SUPPORT
-CFLAGS+=	-I${ZFSSRC}
-CFLAGS+=	-I${SYSDIR}/cddl/boot/zfs
-LIBZFSBOOT=	${BOOTOBJ}/zfs/libzfsboot.a
-.endif
 
 # Always add MI sources
 .include	"${BOOTSRC}/loader.mk"

sys/boot/sparc64/zfsloader/Makefile

@@ -4,6 +4,6 @@
 
 PROG=		zfsloader
 NEWVERSWHAT=	"ZFS enabled bootstrap loader" sparc64
-LOADER_ZFS_SUPPORT=yes
+HAVE_ZFS=	yes
 
 .include "${.CURDIR}/../loader/Makefile"