python,python3: export mk files outside of python package dirs

Since `lang/python` is it's own folder of Python packages
(for both Python 2 & 3), and these build rules are needed
in a lot of packages [especially Python packages],
putting them here makes sense architecturally,
to be shared.

This also helps get rid of the `include_mk` construct
which relies on OpenWrt core to provide, and seems
like a broken design idea that has persisted for a while.
Reason is: it requires that Python 2/3 be built to provide
these mk files for other Python packages,
which seems like a bad idea.

Long-term, there could be an issue where some other feeds
would require these mk files [e.g. telephony] for
some Python packages.
We'll see how we handle this a bit later.

For now we limit this to this feed.

Signed-off-by: Alexandru Ardelean <ardeleanalex@gmail.com>

lang/python/python-host.mk

@@ -0,0 +1,97 @@
+#
+# Copyright (C) 2015-2016 OpenWrt.org
+#
+# This is free software, licensed under the GNU General Public License v2.
+# See /LICENSE for more information.
+#
+
+# Note: include this after `include $(TOPDIR)/rules.mk in your package Makefile
+#       if `python-package.mk` is included, this will already be included
+
+ifneq ($(__python_host_mk_inc),1)
+__python_host_mk_inc=1
+
+# For PYTHON_VERSION
+python_mk_path:=$(dir $(lastword $(MAKEFILE_LIST)))
+include $(python_mk_path)python-version.mk
+
+HOST_PYTHON_DIR:=$(STAGING_DIR_HOSTPKG)
+HOST_PYTHON_INC_DIR:=$(HOST_PYTHON_DIR)/include/python$(PYTHON_VERSION)
+HOST_PYTHON_LIB_DIR:=$(HOST_PYTHON_DIR)/lib/python$(PYTHON_VERSION)
+
+HOST_PYTHON_PKG_DIR:=$(HOST_PYTHON_DIR)/lib/python$(PYTHON_VERSION)/site-packages
+
+HOST_PYTHON_BIN:=$(HOST_PYTHON_DIR)/bin/python$(PYTHON_VERSION)
+
+HOST_PYTHONPATH:=$(HOST_PYTHON_LIB_DIR):$(HOST_PYTHON_PKG_DIR)
+
+define HostPython
+	if [ "$(strip $(3))" == "HOST" ]; then \
+		export PYTHONPATH="$(HOST_PYTHONPATH)"; \
+		export PYTHONDONTWRITEBYTECODE=0; \
+	else \
+		export PYTHONPATH="$(PYTHONPATH)"; \
+		export PYTHONDONTWRITEBYTECODE=1; \
+		export _python_sysroot="$(STAGING_DIR)"; \
+		export _python_prefix="/usr"; \
+		export _python_exec_prefix="/usr"; \
+	fi; \
+	export PYTHONOPTIMIZE=""; \
+	$(1) \
+	$(HOST_PYTHON_BIN) $(2);
+endef
+
+define host_python_settings
+	ARCH="$(HOST_ARCH)" \
+	CC="$(HOSTCC)" \
+	CCSHARED="$(HOSTCC) $(HOST_FPIC)" \
+	CXX="$(HOSTCXX)" \
+	LD="$(HOSTCC)" \
+	LDSHARED="$(HOSTCC) -shared" \
+	CFLAGS="$(HOST_CFLAGS)" \
+	CPPFLAGS="$(HOST_CPPFLAGS) -I$(HOST_PYTHON_INC_DIR)" \
+	LDFLAGS="$(HOST_LDFLAGS) -lpython$(PYTHON_VERSION) -Wl$(comma)-rpath=$(STAGING_DIR_HOSTPKG)/lib" \
+	_PYTHON_HOST_PLATFORM=linux2
+endef
+
+# $(1) => commands to execute before running pythons script
+# $(2) => python script and its arguments
+# $(3) => additional variables
+define Build/Compile/HostPyRunHost
+	$(call HostPython, \
+		$(if $(1),$(1);) \
+		$(call host_python_settings) \
+		$(3) \
+		, \
+		$(2) \
+		, \
+		HOST \
+	)
+endef
+
+# Note: I shamelessly copied this from Yousong's logic (from python-packages);
+HOST_PYTHON_PIP:=$(STAGING_DIR_HOSTPKG)/bin/pip$(PYTHON_VERSION)
+define host_python_pip_install
+	$(call host_python_settings) \
+	$(HOST_PYTHON_PIP) install \
+		--root=$(1) \
+		--prefix=$(2) \
+		--ignore-installed \
+		$(3)
+endef
+
+define host_python_pip_install_host
+$(call host_python_pip_install,$(STAGING_DIR_HOSTPKG),"",$(1))
+endef
+
+# $(1) => build subdir
+# $(2) => additional arguments to setup.py
+# $(3) => additional variables
+define Build/Compile/HostPyMod
+	$(call Build/Compile/HostPyRunHost, \
+		cd $(HOST_BUILD_DIR)/$(strip $(1)), \
+		./setup.py $(2), \
+		$(3))
+endef
+
+endif # __python_host_mk_inc