Apply upstream fixes of several buffer overflow issues:

r1555 Fix forward reference offset bug.
r1556 Fix forward referencing bugs.
r1557 Fix buffer overflow for repeated conditional when referencing a

duplicate name.

r1558 Fix buffer overflow for named recursive back reference when the

name is duplicated.

r1559 Fix named forward reference to duplicate group number overflow

bug.

r1560 Fix buffer overflow for lookbehind within mutually recursive

subroutines.

r1562 Fix another buffer overflow.

Note that regression tests were not included in this patchset, however
the actual test cases have been run against both old and new code to
make sure that the issues were fixed properly.

With hat: so
Obtained from: PCRE svn (revisions detalied above)
MFH: 2015Q2
Security: CVE-2015-3210, CVE-2015-3217