Fix PCRE errors in xbmc.log > add recommended configure flags to PCRE in CmakeLists.txt

I noticed this in the xbmc.log a while back but forgot about until today.
WARNING: UTF-8 is not supported in PCRE lib, support for national symbols is limited!
WARNING: Unicode properties are not enabled in PCRE lib, support for national symbols may be limited!
NOTICE: Consider installing PCRE lib version 8.10 or later with enabled Unicode properties and UTF-8 support. Your PCRE lib version: 8.33 2013-05-28

Added configure flags as per this post at XBMC github :-
https://github.com/Karlson2k/xbmc/commit/d0dc3327dc39b75b812985075da42984d1a25902