bpo-32885: Tools/scripts/pathfix.py: Add -n option for no backup~ (#5772)

Creating backup files with ~ suffix can be undesirable in some environment,
such as when building RPM packages. Instead of requiring the user to remove
those files manually, option -n was added, that simply disables this feature.

-n was selected because 2to3 has the same option with this behavior.
diff --git a/Misc/ACKS b/Misc/ACKS
index d8179c8..d752d8a 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -687,6 +687,7 @@
 Brad Howes
 Mike Hoy
 Ben Hoyt
+Miro Hrončok
 Chiu-Hsiang Hsu
 Chih-Hao Huang
 Christian Hudon
diff --git a/Misc/NEWS.d/next/Tools-Demos/2018-02-20-12-16-47.bpo-32885.dL5x7C.rst b/Misc/NEWS.d/next/Tools-Demos/2018-02-20-12-16-47.bpo-32885.dL5x7C.rst
new file mode 100644
index 0000000..e003e1d
--- /dev/null
+++ b/Misc/NEWS.d/next/Tools-Demos/2018-02-20-12-16-47.bpo-32885.dL5x7C.rst
@@ -0,0 +1,2 @@
+Add an ``-n`` flag for ``Tools/scripts/pathfix.py`` to disbale automatic
+backup creation (files with ``~`` suffix).