build: Request python2 for all directly executed python binaries

Some systems point python to python3 instead of python2 - explicitly
request python2 to avoid conflicts.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/console.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 # Script to implement a test console with firmware over serial port
 #
 # Copyright (C) 2016,2017  Kevin O'Connor <kevin@koconnor.net>

klippy/klippy.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 # Main code for host side printer firmware
 #
 # Copyright (C) 2016  Kevin O'Connor <kevin@koconnor.net>

klippy/parsedump.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 # Script to parse a serial port data dump
 #
 # Copyright (C) 2016  Kevin O'Connor <kevin@koconnor.net>

scripts/avrsim.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 # Script to interact with simulavr by simulating a serial port.
 #
 # Copyright (C) 2015  Kevin O'Connor <kevin@koconnor.net>

scripts/buildcommands.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 # Script to handle build time requests embedded in C code.
 #
 # Copyright (C) 2016  Kevin O'Connor <kevin@koconnor.net>

scripts/checkstack.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 # Script that tries to find how much stack space each function in an
 # object is using.
 #

scripts/graphstats.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 # Script to parse a logging file, extract the stats, and graph them
 #
 # Copyright (C) 2016  Kevin O'Connor <kevin@koconnor.net>

scripts/stepstats.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python2
 # Script to calculate stats for each stepper from a log of messages
 #
 # Copyright (C) 2016  Kevin O'Connor <kevin@koconnor.net>