[clang] [Clang] Fix FixIt for implicit-int diagnostics. (PR #179356)

[via cfe-commits]

Sirraide wrote:

Also can you add some more tests along the lines of
```c
const x;
static y;
static const z;
// etc.
```
and see if the fixit still works (I would assume so but I’m not sure we have tests for that atm).

https://github.com/llvm/llvm-project/pull/179356