fixup of #1054 - _PostBlitType should be private
Merge pull request #1058 from MartinNowak/fixup1054

fixup of #1054 - _PostBlitType should be private
squash all the changes into one commit (note: that includes the merge from upstream that I did).
Merge branch 'master' of github.com:daym/druntime
Merge remote-tracking branch 'upstream/master'