package/jailhouse: expand PKG_PYTHON_SETUPTOOLS_INSTALL_TARGET_OPTS

In a follow-up patch, we want to remove this variable. Replace it with
its expansion, which is anyway just
$(PKG_PYTHON_SETUPTOOLS_INSTALL_OPTS) --root=$(TARGET_DIR)

Signed-off-by: Arnout Vandecappelle <arnout@mind.be>
[yann.morin.1998@free.fr:
  - fixup after introduction of JAILHOUSE_INSTALL_HELPER_SCRIPTS
]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/jailhouse/jailhouse.mk

@@ -42,7 +42,8 @@ define JAILHOUSE_INSTALL_HELPER_SCRIPTS
 	$(PKG_PYTHON_SETUPTOOLS_ENV) \
 	$(HOST_DIR)/bin/python setup.py \
 		install --no-compile \
-		$(PKG_PYTHON_SETUPTOOLS_INSTALL_TARGET_OPTS)
+		$(PKG_PYTHON_SETUPTOOLS_INSTALL_OPTS) \
+		--root=$(TARGET_DIR))
 endef
 endif