debian, utils: switch to python 3

Make build and external tests work with python3, so we can drop
the python2 dependency.

This should be merged shortly after osmo-python-tests was migrated to
python3, and the jenkins build slaves were (automatically) updated to
have the new osmo-python-tests installed.

Related: OS#2819
Depends: osmo-python-tests I3ffc3519bf6c22536a49dad7a966188ddad351a7
Change-Id: I84ef43f700e125c7a65f92347f12844e07e65655

debian/control

@@ -16,7 +16,7 @@ Build-Depends: debhelper (>= 9),
                pkg-config,
                libtalloc-dev,
                libsctp-dev,
-               python (>= 2.7.6)
+               python3
 Standards-Version: 3.9.8
 Vcs-Git: git://git.osmocom.org/libosmocore.git
 Vcs-Browser: http://git.osmocom.org/libosmocore/

include/Makefile.am

@@ -179,7 +179,7 @@ osmocom/core/crc%gen.h: osmocom/core/crcXXgen.h.tpl
 	$(AM_V_GEN)sed -e's/XX/$*/g' $< > $@
 
 osmocom/gsm/gsm0503.h: $(top_srcdir)/utils/conv_gen.py $(top_srcdir)/utils/conv_codes_gsm.py
-	$(AM_V_GEN)python $(top_srcdir)/utils/conv_gen.py gen_header gsm \
+	$(AM_V_GEN)python3 $(top_srcdir)/utils/conv_gen.py gen_header gsm \
 		--target-path $(builddir)/osmocom/gsm
 
 CLEANFILES = osmocom/gsm/gsm0503.h

src/gsm/Makefile.am

@@ -49,6 +49,6 @@ EXTRA_DIST = libosmogsm.map
 
 # Convolutional codes generation
 gsm0503_conv.c: $(top_srcdir)/utils/conv_gen.py $(top_srcdir)/utils/conv_codes_gsm.py
-	$(AM_V_GEN)python $(top_srcdir)/utils/conv_gen.py gen_codes gsm
+	$(AM_V_GEN)python3 $(top_srcdir)/utils/conv_gen.py gen_codes gsm
 
 CLEANFILES = gsm0503_conv.c

tests/Makefile.am

@@ -362,7 +362,7 @@ $(TESTSUITE): $(srcdir)/testsuite.at $(srcdir)/package.m4
 	mv $@.tmp $@
 
 conv/gsm0503_test_vectors.c: $(top_srcdir)/utils/conv_gen.py $(top_srcdir)/utils/conv_codes_gsm.py
-	$(AM_V_GEN)python $(top_srcdir)/utils/conv_gen.py gen_vectors gsm \
+	$(AM_V_GEN)python3 $(top_srcdir)/utils/conv_gen.py gen_vectors gsm \
 		--target-path $(builddir)/conv
 
 if ENABLE_EXT_TESTS

utils/conv_codes_gsm.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
 from conv_gen import ConvolutionalCode

utils/conv_gen.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 mod_license = """
 /*