include/host-build.mk: use STAGING_DIR_HOSTPKG

Instead of hardcoding $(STAGING_DIR)/host, use the new $(STAGING_DIR_HOSTPKG)
variable to refer to the directory.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

include/host-build.mk

@@ -30,7 +30,7 @@ BUILD_TYPES += host
 HOST_STAMP_PREPARED=$(HOST_BUILD_DIR)/.prepared$(if $(HOST_QUILT)$(DUMP),,$(shell $(call find_md5,${CURDIR} $(PKG_FILE_DEPENDS),)))
 HOST_STAMP_CONFIGURED:=$(HOST_BUILD_DIR)/.configured
 HOST_STAMP_BUILT:=$(HOST_BUILD_DIR)/.built
-HOST_BUILD_PREFIX:=$(if $(IS_PACKAGE_BUILD),$(STAGING_DIR)/host,$(STAGING_DIR_HOST))
+HOST_BUILD_PREFIX:=$(if $(IS_PACKAGE_BUILD),$(STAGING_DIR_HOSTPKG),$(STAGING_DIR_HOST))
 HOST_STAMP_INSTALLED:=$(HOST_BUILD_PREFIX)/stamp/.$(PKG_NAME)_installed
 
 override MAKEFLAGS=