python-lxml: allow build as host package

While currently there is no in-tree Buildroot package which depends on
host-python-lxml, we (DATACOM) have some proprietary modules that use it
in their test scripts.

We tested python-lxml as host package and confirmed that it builds and
works correctly. Someone else might require it, so we are proposing its
inclusion.

Signed-off-by: Carlos Santos <casantos@datacom.ind.br>
[Thomas: add Config.in.host entry.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/Config.in.host

@@ -36,6 +36,7 @@ menu "Host utilities"
 	source "package/patchelf/Config.in.host"
 	source "package/pru-software-support/Config.in.host"
 	source "package/pwgen/Config.in.host"
+	source "package/python-lxml/Config.in.host"
 	source "package/qemu/Config.in.host"
 	source "package/raspberrypi-usbboot/Config.in.host"
 	source "package/s6-rc/Config.in.host"

package/python-lxml/Config.in.host

@@ -0,0 +1,8 @@
+config BR2_PACKAGE_HOST_PYTHON_LXML
+	bool "host python-lxml"
+	help
+	  The lxml XML toolkit is a Pythonic binding for the C libraries
+	  libxml2 and libxslt.
+
+	  http://lxml.de/
+

package/python-lxml/python-lxml.mk

@@ -21,11 +21,16 @@ PYTHON_LXML_LICENSE_FILES = \
 PYTHON_LXML_SETUP_TYPE = setuptools
 
 PYTHON_LXML_DEPENDENCIES = libxml2 libxslt zlib
+HOST_PYTHON_LXML_DEPENDENCIES = host-libxml2 host-libxslt host-zlib
 
 # python-lxml needs these scripts in order to properly detect libxml2 and
 # libxslt compiler and linker flags
 PYTHON_LXML_BUILD_OPTS = \
 	--with-xslt-config=$(STAGING_DIR)/usr/bin/xslt-config \
 	--with-xml2-config=$(STAGING_DIR)/usr/bin/xml2-config
+HOST_PYTHON_LXML_BUILD_OPTS = \
+	--with-xslt-config=$(HOST_DIR)/usr/bin/xslt-config \
+	--with-xml2-config=$(HOST_DIR)/usr/bin/xml2-config
 
 $(eval $(python-package))
+$(eval $(host-python-package))