split: switch to getline() for line/pattern matching

[kevans]

Summary

split: switch to getline() for line/pattern matching

Get rid of split's home-grown logic for growing the buffer; arbitrarily
breaking at LONG_MAX bytes instead of 65536 bytes gives us much more
wiggle room.  Additionally, we'll actually fail out entirely if we can't
fit a line, which makes noticing this class of problem much easier.

Sponsored by:   Klara, Inc.
Differential Revision:  https://reviews.freebsd.org/D36323

[gbe]

Thanks for working on this, LGTM for the man page part.

[pauamma_gundo.com]

usr.bin/split/split.1

215–219

Make it more obvious that the restriction was removed.

[kevans]

Address review commente

[pauamma_gundo.com]

usr.bin/split/split.1

219

Did you mean to add something after "and"?

[kevans]

usr.bin/split/split.1

219

whoops: "the -l flag's line counting"

[bapt]

usr.bin/split/split.c

283–284

why not use getline(3) here?

[pauamma_gundo.com]

usr.bin/split/split.1

31

Bump on commit.

[kevans]

Switch to getline() for split2's buffer management, move the global buf/bufsize
into split1() and keep that at MAXBSIZE.

[kevans]

Clean up the diff a bit more; don't rename bfr -> buf for split1(), but maintain
the MAXBSIZE -> sizeof(bfr) change.

[pauamma_gundo.com]

Manual page change looks good and consistent with the change summary.