boost: enable single/multi/shared/static libs.

* Add option to disable single threading variant.
* Add option to disable static library variant.
* Drop unneeded "--with-system-layout" option.

Closes #21298.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
concurrencykit 0.2.20

Closes #21313.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>