[mlir] Avoid crash in mlir-query's MatchFinder class (#145049)
It was failing for cases where the location was not a FileLineColLoc and fileLoc a nullptr.
If the following query is run:
`match getUsersByPredicate(hasOpName("memref.alloc"),
hasOpName("memref.dealloc"), true)`
on the IR illustrated below, it caused the program to crash.
``` mlir
func.func @slicing_linalg_op(%arg0 : index, %arg1 : index, %arg2 : index) {
%a = memref.alloc(%arg0, %arg2) : memref<?x?xf32>
%b = memref.alloc(%arg2, %arg1) : memref<?x?xf32>
%c = memref.alloc(%arg0, %arg1) : memref<?x?xf32>
%d = memref.alloc(%arg0, %arg1) : memref<?x?xf32>
linalg.matmul ins(%a, %b : memref<?x?xf32>, memref<?x?xf32>)
outs(%c : memref<?x?xf32>)
linalg.matmul ins(%a, %b : memref<?x?xf32>, memref<?x?xf32>)
outs(%d : memref<?x?xf32>)
memref.dealloc %c : memref<?x?xf32>
memref.dealloc %b : memref<?x?xf32>
memref.dealloc %a : memref<?x?xf32>
memref.dealloc %d : memref<?x?xf32>
return
}
```
e89bd48c56