Update bundled PCRE2-library to version 10.23

Some manual changes done to the library were lost with this update.
They will be added in the next commit.

pcre2/NEWS

@@ -1,6 +1,105 @@
 News about PCRE2 releases
 -------------------------
 
+Version 10.23 14-February-2017
+------------------------------
+
+1. ChangeLog has the details of a lot of bug fixes and tidies.
+
+2. There has been a major re-factoring of the pcre2_compile.c file. Most syntax
+checking is now done in the pre-pass that identifies capturing groups. This has
+reduced the amount of duplication and made the code tidier. While doing this,
+some minor bugs and Perl incompatibilities were fixed (see ChangeLog for
+details.)
+
+3. Back references are now permitted in lookbehind assertions when there are
+no duplicated group numbers (that is, (?| has not been used), and, if the
+reference is by name, there is only one group of that name. The referenced
+group must, of course be of fixed length.
+
+4. \g{+<number>} (e.g. \g{+2} ) is now supported. It is a "forward back
+reference" and can be useful in repetitions (compare \g{-<number>} ). Perl does
+not recognize this syntax.
+
+5. pcre2grep now automatically expands its buffer up to a maximum set by
+--max-buffer-size.
+
+6. The -t option (grand total) has been added to pcre2grep.
+
+7. A new function called pcre2_code_copy_with_tables() exists to copy a
+compiled pattern along with a private copy of the character tables that is
+uses.
+
+8. A user supplied a number of patches to upgrade pcre2grep under Windows and
+tidy the code.
+
+9. Several updates have been made to pcre2test and test scripts (see
+ChangeLog).
+
+
+Version 10.22 29-July-2016
+--------------------------
+
+1. ChangeLog has the details of a number of bug fixes.
+
+2. The POSIX wrapper function regcomp() did not used to support back references
+and subroutine calls if called with the REG_NOSUB option. It now does.
+
+3. A new function, pcre2_code_copy(), is added, to make a copy of a compiled
+pattern.
+
+4. Support for string callouts is added to pcre2grep.
+
+5. Added the PCRE2_NO_JIT option to pcre2_match().
+
+6. The pcre2_get_error_message() function now returns with a negative error
+code if the error number it is given is unknown.
+
+7. Several updates have been made to pcre2test and test scripts (see
+ChangeLog).
+
+
+Version 10.21 12-January-2016
+-----------------------------
+
+1. Many bugs have been fixed. A large number of them were provoked only by very
+strange pattern input, and were discovered by fuzzers. Some others were
+discovered by code auditing. See ChangeLog for details.
+
+2. The Unicode tables have been updated to Unicode version 8.0.0.
+
+3. For Perl compatibility in EBCDIC environments, ranges such as a-z in a
+class, where both values are literal letters in the same case, omit the
+non-letter EBCDIC code points within the range.
+
+4. There have been a number of enhancements to the pcre2_substitute() function,
+giving more flexibility to replacement facilities. It is now also possible to
+cause the function to return the needed buffer size if the one given is too
+small.
+
+5. The PCRE2_ALT_VERBNAMES option causes the "name" parts of special verbs such
+as (*THEN:name) to be processed for backslashes and to take note of
+PCRE2_EXTENDED.
+
+6. PCRE2_INFO_HASBACKSLASHC makes it possible for a client to find out if a
+pattern uses \C, and --never-backslash-C makes it possible to compile a version
+PCRE2 in which the use of \C is always forbidden.
+
+7. A limit to the length of pattern that can be handled can now be set by
+calling pcre2_set_max_pattern_length().
+
+8. When matching an unanchored pattern, a match can be required to begin within
+a given number of code units after the start of the subject by calling
+pcre2_set_offset_limit().
+
+9. The pcre2test program has been extended to test new facilities, and it can
+now run the tests when LF on its own is not a valid newline sequence.
+
+10. The RunTest script has also been updated to enable more tests to be run.
+
+11. There have been some minor performance enhancements.
+
+
 Version 10.20 30-June-2015
 --------------------------