ExplicitLevelImports: check re-exports
Aux.hs
```hs
{-# LANGUAGE ExplicitLevelImports, TemplateHaskell #-}
module Aux where
import Language.Haskell.TH
a :: Q Exp
a = [| True |]
```
M.hs
```hs
{-# LANGUAGE ExplicitLevelImports, TemplateHaskell #-}
module M (a) where
import quote Aux
```
Attempting to compile `ghc M` with head works. However, this is wrong: re-exports are always on level 0, while we've imported `Aux` only for use in quotes. This can be used to trigger a crash:
Crash.hs
```
{-# LANGUAGE ExplicitLevelImports #-}
module Crash where
import splice M
x :: Bool
x = $(a)
```
```
$ ./stage1/bin/ghc -fno-code -fforce-recomp Crash
[1 of 3] Compiling Aux ( Aux.hs, nothing )
[2 of 3] Compiling M ( M.hs, /tmp/nix-shell.OClGQp/ghc34004_tmp_1/ghc_tmp_3.o )
[3 of 3] Compiling Crash ( Crash.hs, nothing )
<no location info>: error:
panic! (the 'impossible' happened)
GHC version 9.13.20250602:
expectJust
Call stack:
CallStack (from HasCallStack):
pprPanic, called at compiler/GHC/Data/Maybe.hs:77:19 in ghc-9.13-inplace:GHC.Data.Maybe
expectJustError, called at compiler/GHC/Data/Maybe.hs:74:24 in ghc-9.13-inplace:GHC.Data.Maybe
expectJust, called at compiler/GHC/Linker/Deps.hs:157:45 in ghc-9.13-inplace:GHC.Linker.Deps
Please report this as a GHC bug: https://www.haskell.org/ghc/reportabug
```
Noticed by @mpickering.
issue