Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Trim down libcompat by removing <regexp.h>.

Erwin ran an exp-run with libcompat and <regexp.h> removed. It turns out
the regexp library is almost entirely unused. In fact, it looks like it
is sometimes used by accident. Because these function names clash with
libc's <regex.h>, some application use both <regex.h> and libcompat,
which means they link against the wrong regex library.

This commit removes the regexp library and reimplements re_comp() and
re_exec() using <regex.h>. It seems the grammar of the regular
expressions accepted by these functions is similar to POSIX EREs.

After this commit, 1 low-profile port will be broken, but the maintainer
already has a patch for it sitting in his mailbox.

K&R -> ANSI

Remove California Regent's clause 3, per letter

add a couple of missing #include lines

Add sanity check for "no previous regular expression" state,
bringed by 'more'

Fix bug with searching "" pattern, cause 'more' always shows
next line on "/<Enter>" instead of searching next pattern

This commit was generated by cvs2svn to compensate for changes in r1578,
which included commits to RCS files with non-trunk default branches.

This is James da Silva at the University of Maryland at College Park's
regex.c code as picked up from the net.