uwsgi-cgi: use python3 hostpkg not system python3

On a Debian system without python3-distutils install, uwsgi-cgi was
failing to build because it couldn't import sysconfig from distutils.
OpenWrt packages should be using the OpenWrt python not the system
python. In addition we need to use python3 not python2, even when
both are available.

Signed-off-by: Daniel F. Dickinson <cshored@thecshore.com>

net/uwsgi-cgi/Makefile

@@ -15,6 +15,8 @@ PKG_LICENSE:=GPL-2.0-or-later
 PKG_LICENSE_FILES:=LICENSE
 PKG_MAINTAINER:=Ansuel Smith <ansuelsmth@gmail.com>
 
+PKG_BUILD_DEPENDS:=python3/host
+
 include $(INCLUDE_DIR)/package.mk
 
 define Package/uwsgi-cgi
@@ -39,7 +41,8 @@ define Package/uwsgi-cgi/description
 endef
 
 MAKE_VARS+=\
-	CPP=$(TARGET_CROSS)cpp
+	CPP=$(TARGET_CROSS)cpp \
+	PYTHON=$(STAGING_DIR_HOSTPKG)/bin/python3
 
 define Build/Compile
 	$(call Build/Compile/Default,PROFILE=cgi)

net/uwsgi-cgi/patches/020-uwsgiconfig-system-python3.patch

@@ -0,0 +1,10 @@
+Index: uwsgi-2.0.18/Makefile
+===================================================================
+--- uwsgi-2.0.18.orig/Makefile
++++ uwsgi-2.0.18/Makefile
+@@ -1,4 +1,4 @@
+-PYTHON := python
++PYTHON ?= python3
+ 
+ all:
+ 	$(PYTHON) uwsgiconfig.py --build $(PROFILE)