Preserve named typeglob stringification in package stash values #1927

Summary

Carp::Notify 1.13's export regression tests show that typeglobs read back from a package symbol table lose their names when stringified on PerlOnJava. This is a pure-Perl compatibility regression.

CPAN evidence

• CPAN random-tester run: 20261029-123650-2402
• Previous passing run: 2026-10-07 at commit 66b868f89
• System Perl 5.42.2: all 75 tests pass.
• PerlOnJava: 68/75 assertions pass; 7 fail in t/00_regression.t.
• Each failing assertion compares a package symbol-table hash after use Carp::Notify and gets *null for the exported explode glob where Perl expects the fully qualified name (for example, *t::Carp::Notify::a::explode). The same mismatch appears for packages a through g.
• The distribution is pure Perl; no XS, external service, or platform prerequisite is involved.

The other assertions in t/00_regression.t pass, including checks that the exported code references are the expected functions. The observed failure is specifically the typeglob value exposed through the package stash hash.

Related work

Related typeglob and symbol-table work is tracked in #1119, but that issue does not document this typeglob stringification failure. Please check for overlap while investigating the root cause.

Acceptance criteria

• Add a focused project-owned regression that reads exported glob values from a package stash and compares their stringification with system Perl.
• Validate the regression with standard Perl first.
• Make the focused test pass on JVM and interpreter backends.
• Rerun Carp::Notify 1.13's unchanged upstream suite on both PerlOnJava backends.