pcre2: new package

Signed-off-by: Naoki Matsumoto <n-matsumoto@melcoinc.co.jp>
Signed-off-by: Brent Sink <brents_3@hotmail.com>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
[Thomas:
 - reassign authorship to Naoki Matsumoto
 - add entry to DEVELOPERS file
 - fix broken patch
 - add comment about where the PGP signature was coming from]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>