MFC r314579,r314785:

r314579 (by np):

Add cxgbetool(8) to the base system.

Move cxgbetool from tools/tools to usr.sbin. Compile and install it on
platforms where cxgbe(4) is built by default. Knobs (WITH_CXGBETOOL and
WITHOUT_CXGBETOOL) have been added so that the user can override the
default setting.

r314785:

Fix some trivial manlint warnings

Sentences should begin on new lines, per manlint.

Bump .Dd for the change