Fix local package variable bug - our variables now see local changes

[fglock]

Summary

This fixes the bug where subroutines don't see localized values of our variables set from outside their package.

Problem

package Foo;
our $X = 0;
sub check { print "X=$X\n"; }  # Uses short name

package main;
local $Foo::X = 1;
Foo::check();  # jperl printed "X=0", Perl prints "X=1"

This affected:

• $Carp::CarpLevel (error reporting in all modules using Carp)
• 16+ Log4perl tests
• Many CPAN modules using local $Module::Variable pattern

Root Cause

our variables were treated as lexical (stored in JVM local variable slots), capturing values at subroutine definition time. When local replaced the scalar in the symbol table, the subroutine's cached register still held the old reference.

The Fix

1. EmitVariable.java: Distinguish between:

   • BEGIN-captured our variables (in PerlOnJava::_BEGIN_* packages) → remain lexical for compile-to-runtime persistence
   • Regular our variables → look up from GlobalVariable at runtime

2. EmitSubroutine.java and SubroutineParser.java: Preserve original perlPackage when copying variables to subroutine scopes

3. ScopedSymbolTable.java: Add 4-argument addVariable() overload for explicit package specification

Test Results

• All existing tests pass
• New cross-package our/local tests pass (54 tests in local.t)
• Test::More/Test2 modules work correctly
• BEGIN block lexical persistence works correctly

Test plan

• make passes all unit tests
• local.t includes new cross-package tests
• use Test::More works correctly
• BEGIN block persistence works correctly

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