Allow users to use a non-system version of perl, python and awk, which is useful
in certain package managers.
Reviewed By: JDevlieghere, MaskRay
Differential Revision: https://reviews.llvm.org/D95119
Using from __future__ import print_function it is possible to have a compatible behavior of `print(...)` across Python version.
Differential Revision: https://reviews.llvm.org/D55213
llvm-svn: 349454