TBB Win7: Fix permissions after sed -i
When building TBB on Windows 7 (or Vista) with UAC enabled, 'sed -i' does not copy permissions and the edited file becomes read-only. sed gets a Permission Denied when accessing (or setting) permissions when UAC is enabled. This patch is a simple workaround that adds write permission again so that later appends work (specifically in 'write-tbb-version'.)
The branch name is 'fix-sed-inplace', my public tpo repo.