syslinux: install helper programs to the host

Even though syslinux is built for the target, it does create helper
programs intended to be run on the host such as syslinux and extlinux.
This change installs these helper programs to the host so that they may be
called by post image creation scripts.

Signed-off-by: Frank Hunleth <fhunleth@troodon-software.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

boot/syslinux/syslinux.mk

@@ -11,7 +11,6 @@ SYSLINUX_SITE    = $(BR2_KERNEL_MIRROR)/linux/utils/boot/syslinux/4.xx/
 SYSLINUX_LICENSE = GPLv2+
 SYSLINUX_LICENSE_FILES = COPYING
 
-SYSLINUX_INSTALL_TARGET = NO
 SYSLINUX_INSTALL_IMAGES = YES
 
 SYSLINUX_DEPENDENCIES = host-nasm host-util-linux
@@ -23,6 +22,12 @@ define SYSLINUX_BUILD_CMDS
 	$(TARGET_MAKE_ENV) $(MAKE) CC="$(HOSTCC) -idirafter $(HOST_DIR)/usr/include $(HOST_LDFLAGS)" AR="$(HOSTAR)" -C $(@D)
 endef
 
+define SYSLINUX_INSTALL_TARGET_CMDS
+	# While the actual bootloader is compiled for the target, several
+	# utilities for installing the bootloader are meant for the host.
+	$(TARGET_MAKE_ENV) $(MAKE) -C $(@D) INSTALLROOT=$(HOST_DIR) install
+endef
+
 SYSLINUX_IMAGES-$(BR2_TARGET_SYSLINUX_ISOLINUX) += isolinux.bin
 SYSLINUX_IMAGES-$(BR2_TARGET_SYSLINUX_PXELINUX) += pxelinux.bin