Fix $^H scope leakage and add I18N::Langinfo module

[fglock]

Summary

This PR includes several related fixes discovered during DateTime/I18N::Langinfo testing:

1. Fix version->parse() to handle undef values (Version.java)

Fixes "Invalid version format (non-numeric data)" error when MM->parse_version() returns undef or the literal string "undef" for modules without version numbers.

2. Fix $^H scope leakage (ScalarSpecialVariable.java)

Fixes a bug where use locale (or any module modifying $^H) after use Test::More was incorrectly enabling strict mode in the outer scope.

Problem: The $^H (compile-time hints) special variable was caching values in a shared lvalue field. When Test::More enabled strict mode, the strict bits got cached. Later when locale.pm read $^H, it got the stale cached value.

Fix:

• Remove lvalue caching for HINTS in vivify()
• Change set() to only update the scope's strict options via symbol table
• Change getValueAsScalar() HINTS case to always read from current scope's symbol table

3. Fix $^H propagation between BEGIN blocks (PerlLanguageProvider.java)

Fixes $^H values not persisting between BEGIN blocks in the same lexical scope.

Fix: Propagate $^H (strictOptions) bi-directionally between caller scope and BEGIN block execution scope.

4. Add I18N::Langinfo module

• I18NLanginfo.java: Java XS implementation with langinfo() function and ~70 locale constants
• I18N/Langinfo.pm: Imported from Perl 5 distribution
• constant.pm: Updated to full Perl 5 version with /u modifier for Unicode constant names

5. Fix warnings::enabled() (Warnings.java)

Allow warnings::enabled() to be called without arguments (checks if warnings are enabled for the calling package). Required by the full Perl 5 constant.pm.

6. Fix ${qr//} dereference with strict refs (RuntimeScalar.java)

Add REGEX case to scalarDeref() to handle dereferencing Regexp objects. In Perl, ${qr/foo/} returns the stringified form "(?^:foo)". Previously this threw "Not a SCALAR reference" under strict refs.

Test plan

• Original $^H scope leakage case passes: ./jperl -e 'use Test::More; use locale; $x = 1; print "OK\n"'
• $^H persists between BEGIN blocks in same lexical scope
• use strict still correctly enforces variable declarations
• I18N::Langinfo works: use I18N::Langinfo qw(langinfo CODESET); print langinfo(CODESET) -> UTF-8
• Unicode constant names work: use utf8; use constant foo => "test"
• ${qr/(?{})/} works with strict refs enabled
• comp/hints.t: 23/31 (improved from 21/31 on master)
• uni/gv.t: 158/206 (same as master)
• uni/stash.t: 33/49 (same as master)
• op/blocks.t: 9/26 (same as master)
• op/index.t: 415/415 (same as master)
• op/utfhash.t: 91/99 (same as master)
• All unit tests pass (make)

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