Use /usr/bin/python2

Part of the effort to port FreeIPA to Arch Linux,
where Python 3 is the default.

FreeIPA hasn't been ported to Python 3, so the code must be modified to
run /usr/bin/python2

https://fedorahosted.org/freeipa/ticket/3438

Updated by pviktori@redhat.com

ipapython/py_default_encoding/Makefile

@@ -1,15 +1,15 @@
-PYTHONLIBDIR ?= $(shell  python -c "from distutils.sysconfig import *; print get_python_lib()")
+PYTHONLIBDIR ?= $(shell  python2 -c "from distutils.sysconfig import *; print get_python_lib()")
 PACKAGEDIR ?= $(DESTDIR)/$(PYTHONLIBDIR)/ipa
 CONFIGDIR ?= $(DESTDIR)/etc/ipa
 
 all:
-	python setup.py build
+	python2 setup.py build
 
 install:
 	if [ "$(DESTDIR)" = "" ]; then \
-		python setup.py install; \
+		python2 setup.py install; \
 	else \
-		python setup.py install --root $(DESTDIR); \
+		python2 setup.py install --root $(DESTDIR); \
 	fi
 
 clean: