fix `@export` for arrays and allow sections on extern variables

previously `@export` for an array would panic with a TODO message.
now it will do the export. However, it uses the variable's name
rather than the name passed to `@export`. Issue #2679 remains open
for that problem.
42ea2d0d1cAndrew Kelley committed on 6/14/2019, 7:28:52 PMparent9e8db5b
3 files changedLine totals unavailable