Defining multiple structs after the same typedef causes compilation error
Hello,

I installed `nimterop` using `nimble`.

Here is the minimum working example:

```nim
# libdpi.nim
import nimterop/cimport

cImport("svdpi.h")

# Input: none
# Return: none
proc hello() {.exportc.} =
  echo "svdpi version: " & svDpiVersion()
  echo "Hello from Nim!"
```

and the [`svdpi.h`][1] (this is a publicly shareable file, so you can add this to your tests too if you like).

On running:

> nim c --out:libdpi.so --app:lib libdpi.nim

I get this error:

```
Hint: unicodeplus [Processing]
Importing /home/kmodi/sandbox/systemverilog/dpi_c/nim_svdpi/svdpi.h
toast --pnim --preprocess /home/kmodi/sandbox/systemverilog/dpi_c/nim_svdpi/svdpi.h
stack trace: (most recent call last)
../../../../.nimble/pkgs/nimterop-0.1.0/nimterop/cimport.nim(230, 22) cImport
../../../../.nimble/pkgs/nimterop-0.1.0/nimterop/cimport.nim(90, 11) getToast
../../../../stow/pkgs/nim/devel/lib/system.nim(3989, 20) failedAssertImpl
../../../../stow/pkgs/nim/devel/lib/system.nim(3982, 11) raiseAssert
../../../../stow/pkgs/nim/devel/lib/system.nim(3016, 7) sysFatal
libdpi.nim(4, 8) template/generic instantiation of `cImport` from here
../../../../stow/pkgs/nim/devel/lib/system.nim(3016, 7) Error: unhandled exception: /home/kmodi/.nimble/pkgs/nimterop-0.1.0/nimterop/cimport.nim(90, 12) `exitCode == 0` 1
```

[1]: https://github.com/kaushalmodi/nim-svdpi/blob/master/includes/svdpi.h