MFC r262499, r262505, r262507, r262509:

MFC r262499, r262505, r262507, r262509:

r262499:
  release.sh:
  - Add a VCSCMD variable that defaults to 'svn checkout',
    and update places 'svn co' is used directly.
  - After sourcing a configuration file, prefix SRCBRANCH,
    PORTBRANCH, and DOCBRANCH with the SVNROOT.
  - Properly capitalize 'FreeBSD.org' in the default SVNROOT.
  - Update Copyright.

  release.conf.sample:
  - Add an example to use git instead of svn, by nullifying
    SVNROOT, and setting SRCBRANCH, DOCBRANCH, and PORTBRANCH
    to the URL fo a git repository.

  release.7:
  - Document VCSCMD.

r262505:
  In release/Makefile, remove exclusion of CVS directories in the
  src/ and ports/ distributions.

  While I am thinking about it, exclude .git directories for src/
  and ports/, as somewhat of a followup to r262499.

r262507:
  Chase r262505, and remove CVS exclusion from picobsd builds.

r262509:
  Rework how WORLD_FLAGS and KERNEL_FLAGS are set, to remove an
  unnecessary expr(1) call.

Sponsored by:	The FreeBSD Foundation

git-svn-id: svn://svn.freebsd.org/base/stable/10@262761 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f