add patch for Tk 8.6.4 to fix problem with tk.tcl not being found

[boegel]

fix for

    window = Tk.Tk()
  File "/user/scratch/gent/vsc400/vsc40023/easybuild_REGTEST/CO7/haswell-ib/software/Python/2.7.10-intel-2015b/lib/python2.7/lib-tk/Tkinter.py", line 1814, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
_tkinter.TclError: Can't find a usable tk.tcl in the following directories: 
    /user/scratch/gent/vsc400/vsc40023/easybuild_REGTEST/CO7/haswell-ib/software/Tcl/8.6.4-intel-2015b/lib/tcl8.6/tk8.6 /user/scratch/gent/vsc400/vsc40023/easybuild_REGTEST/CO7/haswell-ib/software/Tcl/8.6.4-intel-2015b/lib/tk8.6 /user/scratch/gent/vsc400/vsc40023/easybuild_REGTEST/CO7/haswell-ib/software/Python/2.7.10-intel-2015b/lib/tk8.6 /user/scratch/gent/vsc400/vsc40023/easybuild_REGTEST/CO7/haswell-ib/software/Python/lib/tk8.6 /user/scratch/gent/vsc400/vsc40023/easybuild_REGTEST/CO7/haswell-ib/software/Python/2.7.10-intel-2015b/library

see also easybuilders/easybuild-easyblocks#728 (comment)

[boegel]

@wpoely86: please review

[hpcugentbot]

Easyconfigs unit test suite PASSed (see https://jenkins1.ugent.be/job/easybuild-easyconfigs-pr-builder/4922/console for more details).

This pull request is now ready for review/testing.

Please try and find someone who can tackle this; contact @boegel if you're not sure what to do.

[wpoely86]

lgtm

[boegel]

I verified that this patch indeed fixes the problem.

Thanks for the review @wpoely86!

[boegel]

Test report by @boegel
SUCCESS
Build succeeded for 8 out of 8 (8 easyconfigs in this PR)
Linux SL 6.7, Intel(R) Xeon(R) CPU E5-2670 0 @ 2.60GHz, Python 2.6.6
See https://gist.github.com/da1b23866cc9b235007a for a full test report.