fix(ssa): use abi.PathOf() for correct package path in interface metadata

Fixes os.ReadDir segfault caused by package path mismatch between llgo
overlay packages and canonical standard library paths.

The issue occurred in: os.ReadDir → sort.Slice → reflectlite.Swapper
where internal/reflectlite.Type interface has private methods common()
and uncommon(). Using mPkg.Path() returned the overlay path
'github.com/goplus/llgo/runtime/internal/lib/internal/reflectlite'
instead of the canonical 'internal/reflectlite', causing runtime to
only fill public methods and leave private method pointers NULL.

Changed to use abi.PathOf() which returns the correct canonical package
path for matching, ensuring all interface methods (both public and
private) are properly filled in the interface table.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

_demo/go/issue1370_case2/main.go

@@ -7,19 +7,12 @@ import (
 )
 
 func main() {
-	// Create an identifier node
 	ident := &ast.Ident{
 		NamePos: token.Pos(1),
 		Name:    "foo",
 	}
 	
-	// Convert to ast.Expr interface
-	// The ast.Expr interface has a private method exprNode()
-	// Before the fix, this interface conversion would cause segfaults
-	// when calling methods because the PkgPath was incorrectly set
 	var expr ast.Expr = ident
-	
-	// Call methods on the interface
 	fmt.Printf("Identifier: %s\n", ident.Name)
 	fmt.Printf("Position: %d\n", expr.Pos())