Export variables

[keynmol]

They are present in the AST, but aren't exported.

~/p/wonk (main) > cat test.c
extern int hello;

~/p/wonk (main) > bindgen --header test.c --package bla --scala --warning
package bla

import scala.scalanative.unsafe.*
import scala.scalanative.unsigned.*
import scalanative.libc.*
import scalanative.*

~/p/wonk (main) > clang -Xclang -ast-dump -fsyntax-only test.c | grep hello
`-VarDecl 0x15a0ddf98 <test.c:1:1, col:12> col:12 hello 'int' extern

This should generate a

@extern
object variables:
  var hello: CInt = extern