Prodea Alexandru-Liviu authored Mar 07, 2019 and Jose Fonseca committed Mar 12, 2019

This ensures Mesa3D build doesn't fail in this case as encountered when
bisecting Scons source code while regression testing
https://bugs.freedesktop.org/show_bug.cgi?id=109443


and when testing 3.0.5.a.2

Technical details:
Scons version string has consistently been in this format:
MajorVersion.MinorVersion.Patch[.alpha/beta.yyyymmdd]
so these formulas should strip alpha/beta flags and return Scons version:

- as string - `'.'.join(SCons.__version__.split('.')[:3])`
- as tuple of integers - `tuple(map(int, SCons.__version__.split('.')[:3]))`

- v2: Fixed Scons version retrieval formulas as string and tuple of integers.
- v3: Fixed Scons version string format description.

Cc: "19.0" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Jose Fonseca <jfonseca@vmware.com>