add scripts for generating a diff from p4...

awkdiff is the script from scottl that he got from ken a long time
ago...  It no longer lives in his home dir, so give it a new home...
This does simple massaging of p4 output to create a useful diff...

The script p4diffbranch will create a diff that includes new and
deleted files unlike the normal diff2 -b command...  So will be useful
for extracting patches from p4...  It does take a changeset that will
be used to diff against...


git-svn-id: svn+ssh://svn.freebsd.org/base/head@270727 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f