Ports libpcrecpp to pcre2

Ports the c++ wrapper around pcre to pcre2 and doing
some modifications on the way.

- Lifts the limitation of matching arguments that
  could be passed to the members of pcrecpp::RE without
  changing the API.

- The newline mode can no longer be specified as an option
  flag. Instead it must be passed to the pattern compiler using
  a compile context. Therefore, a member was added to REOptions,
  holding the newline mode.

- The PCRE_EXTRA option has no equivalent in pcre2 and was
  removed.

Merged-In: I0bd5da97128fda25b8b2014c94bed9422540dd67
Bug: 24091652
Change-Id: I0bd5da97128fda25b8b2014c94bed9422540dd67
9 files changed