perldelta: fix reported new version of Carp
fix extrefs text with SDK 2003

The attached patch (also inlined below) fixes the SDK2003 test failure
for me, and also passes with all the other VC++ compilers. (It isn't
easy trying to pinpoint the SDK2003 compiler individually, so it is
simpler to just do this for all VC++ compilers on Windows.)
bump patchlevel to RC3, update hist