StdLib: Add multi-byte character support. The normal "narrow" character set is now...

StdLib: Add multi-byte character support.  The normal "narrow" character set is now UTF-8 instead of ASCII.

Add library classes which are required by StdLib, but not commonly defined in Platform DSC files, to StdLib.inc.
Modify MB_LEN_MAX to be 4, the maximum length of UTF-8 characters.
Adjust size of internal buffers to be multiples of MB_LEN_MAX instead of assuming 1-byte characters.
Make the XYoffset object public and move its declaration into EfiSysCall.h.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: daryl.mcdaniel@intel.com
Reviewed-by: erik.c.bjorge@intel.com
Reviewed-by: lee.g.rosenbaum@intel.com
Reviewed-by: leroy.p.leahy@intel.com
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13457 6f19259b-4bc3-4df7-8a09-765794883524