Global Variables types not persistent across decomps

### Description

Angr-management allows retyping global variable referenced in a function, but these types are reset whenever you try to re-decompile the function.

### Steps to reproduce the bug

- Load and decompile fauxware.
- Select the `sneaky` extern and retype it to 'int*'
- press F5 to re-decompile.

### Environment

_No response_

### Additional context

_No response_