The Gentoo case added by commit 1673923c30 (FindBoost: Add support for
Boost 1.67 with Python version suffixes, 2018-03-18, v3.11.0~3^2) left
out the `.` version component separator and instead duplicated the RPM
case. Add the missing `.` now.
Fixes: #18743
Run the `Utilities/Scripts/clang-format.bash` script to update
all our C++ code to a new style defined by `.clang-format`.
Use `clang-format` version 3.8.
* If you reached this commit for a line in `git blame`, re-run the blame
operation starting at the parent of this commit to see older history
for the content.
* See the parent commit for instructions to rebase a change across this
style transition commit.
