MFC improved vt(4) font generation

r266851: Add VGAROM 8x8, 8x14 and 8x16 fonts for vt(4)

  These are converted from syscons(4) cp437 fonts.

r267306: Add vgarom font source

  These are in 'GNU Unifont' format, and are converted from syscons(4)
  cp437 fonts.

r267400: Add thin versions of VGAROM 8x8 and 8x16 fonts for vt(4)

  These are converted from syscons(4) cp437-thin-8x* fonts.

r267423: Build vt(4) fonts during buildworld

  vtfontcvt(8) is now built during buildworld, so can be used as a
  bootstrap tool to create vt(4) fonts from source .hex or .bdf font
  files, rather than having uuencoded binary fonts in the tree.

r267578: Add glyphs from converted syscons iso* fonts

  This consists of the unique glyphs from the following font files in
  /usr/share/syscons/fonts:

  iso*.fnt     ISO-8859-1 West European
  iso02*.fnt   ISO-8859-2 Central European
  iso04*.fnt   ISO-8859-4 Baltic
  iso05*.fnt   ISO-8859-5 Cyrillic
  iso07*.fnt   ISO-8859-7 Greek
  iso08*.fnt   ISO-8859-8 Hebrew
  iso09*.fnt   ISO-8859-9 Turkish
  iso15*.fnt   ISO-8859-15 West European

r268022: Rename the WITHOUT_VT_SUPPORT knob to WITHOUT_VT

  The _SUPPORT knobs have a consistent meaning which differs from the
  behaviour controlled by this knob.  As the knob is opt-out and has not
  appeared in a release the impact should be low.

Approved by:	re
Sponsored by:	The FreeBSD Foundation