scons: Compatibility with Scons development version string
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> (cherry picked from commit 7f89fd17)