Add a python3 meta-package which uses python.port.mk to automatically depend

on whatever is the current default version of python 3 in the ports tree
(currently 3.7). Allows adding it with pkg_add python3 rather than needing to
know the correct subdir name (as you would with pkg_add python%3.7).
Deliberately not adding a similar one for py2 which is not likely to
proceed beyond 2.7.

ok kmos@, aja@ pirofti@ zhuk@ like it too

meta/Makefile

@@ -1,4 +1,4 @@
-# $OpenBSD: Makefile,v 1.14 2018/12/10 15:31:52 robert Exp $
+# $OpenBSD: Makefile,v 1.15 2020/01/07 20:01:20 sthen Exp $
 
      SUBDIR =
      SUBDIR += avr
@@ -10,6 +10,7 @@
      SUBDIR += mate
      SUBDIR += msp430
      SUBDIR += mupen64plus
+     SUBDIR += python3
      SUBDIR += qt5
      SUBDIR += tor-browser
      SUBDIR += xfce

meta/python3/Makefile

@@ -0,0 +1,11 @@
+# $OpenBSD: Makefile,v 1.1 2020/01/07 20:01:20 sthen Exp $
+
+COMMENT =	meta-package to install the current version of python 3
+
+PKGNAME =	python3-${MODPY_DEFAULT_VERSION_3}
+
+MODULES =	lang/python
+MODPY_VERSION =	${MODPY_DEFAULT_VERSION_3}
+MODPY_BUILDDEP = No
+
+.include <bsd.port.mk>

meta/python3/pkg/DESCR

@@ -0,0 +1,3 @@
+This is simply a meta-package which depends on the current version of
+Python 3, allowing easy installation with "pkg_add python3" without
+having to worry about the particular version number.

meta/python3/pkg/PLIST

@@ -0,0 +1 @@
+@comment $OpenBSD: PLIST,v 1.1 2020/01/07 20:01:20 sthen Exp $