Replace /usr/bin/python with /usr/env/python

/usr/bin/python doesn't exist on ubuntu 20.04 causing tests to fail.
I've updated the shebangs everywhere to use `/usr/bin/env python`
instead.

Author: etcwilde

benchmark/scripts/compare_perf_tests.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
 # ===--- compare_perf_tests.py -------------------------------------------===//

benchmark/scripts/test_Benchmark_Driver.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
 # ===--- test_Benchmark_Driver.py ----------------------------------------===//

benchmark/scripts/test_compare_perf_tests.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
 # ===--- test_compare_perf_tests.py --------------------------------------===//

benchmark/scripts/test_utils.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
 # ===--- test_utils.py ---------------------------------------------------===//

test/ScanDependencies/Inputs/CommandRunner.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 import subprocess
 import sys

utils/jobstats/__init__.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 #
 # ==-- jobstats - support for reading the contents of stats dirs --==#
 #

utils/jobstats/jobstats.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 #
 # ==-- jobstats - support for reading the contents of stats dirs --==#
 #

utils/process-stats-dir.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 #
 # ==-- process-stats-dir - summarize one or more Swift -stats-output-dirs --==#
 #

utils/rusage.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # utils/rusage.py - Utility to measure resource usage -*- python -*-
 #
 # This source file is part of the Swift.org open source project

validation-test/ParseableInterface/verify_all_overlays.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 # Note that this test should still "pass" when no swiftinterfaces have been
 # generated.