Fix type name in ptype-o.exp

Fix type name in ptype-o.exp

The "Rec" type in ptype-o.exp is currently named "prog__rec" by the
compiler.  However, with my changes to GNAT, the type will no longer
have a prefix, as it is local to a procedure.

Changing this to just use "rec" works fine with the new compiler, but
then fails with older compilers.  To allow correct operation with both
compilers, this patch simply moves the type into a new package.  This
doesn't affect the meaning of the test, which is just ensuring that
ptype/o works in a certain case.

Note that the more obvious fix of just using "ptype/o rec" does not
work with the current GNAT.  I haven't investigated this but I did
file a bug to track it:

    https://sourceware.org/bugzilla/show_bug.cgi?id=32169