Use /usr/bin/env python instead of /usr/bin/python.

On operating systems like the BSDs, it is typically the case that
/usr/bin/python does not exist. We should therefore use /usr/bin/env
instead. This is also done in various other scripts in tools/.

llvm-svn: 216945

clang/tools/clang-format/clang-format-diff.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 #
 #===- clang-format-diff.py - ClangFormat Diff Reformatter ----*- python -*--===#
 #