Smarter handling of escaped semicolons in vmsify.

In theory, a Unix-format filespec can contain a semicolon and thus
need to be escaped when converted to a VMS-format filespec.  But
a much more common use case is a filespec that has a version
number despite being in Unix format.

So detect a semicolon that delimits a version specification and
pass it through but escape other semicolons.  This is apparently
what decc$to_vms does, so we're being consistent with the CRTL.
Attribute::Handlers update/changelog and version bump
Filter::Simple update/changelog and version bump
Data::Dumper update/changelog and version bump
sv.h: add some more flag usage commentary

Also, move SVphv_SHAREKEYS up to be closer to SVf_UTF8 - they are the same
flag bit, but it wasn't clear, since there was a big gap between them
make core safe against HvAUX() realloc

Since the HvAUX structure is just tacked onto the end of the HvARRAY()
struct, code like this can do bad things:

    aux = HvAUX();
    ... something that might split hv ...
    aux->foo = ...; /* SEGV! */

So I've visually audited core for places where HbAUX() is saved and then
re-used, and re-initialised the var if it looks like HvARRAY() could
have changed in the meantime.

I've been very conservative about what might be unsafe. For example,
destructors or __WARN__ handlers could call perl code that modifies the
hash.
Upgrade to Thread::Queue 3.03
Incorporate changes from CPAN release of ExtUtils-CBuilder