Remove 'device firmware' from various manpages because it is not optional.
usr.bin: fix more mandoc(1) warnings

Unfortunately, most other man pages come from the contrib/ dir,
each with a couple of associated warnings that even sed(1) can't
completely amend.
<wchar.h>: We don't have wcswcs(), so remove prototype.
kernel/pci: Fix extern in pcivar.h and clean up a bit.
Merge branch 'master' into gsocdrm_alter