[mlir] use intptr_t in C API
Using intptr_t is a consensus for MLIR C API, but the change was missing
from 75f239e9756b (that was using unsigned initially) due to a
misrebase.
Reviewed By: stellaraccident, mehdi_amini
Differential Revision: https://reviews.llvm.org/D85751
diff --git a/mlir/docs/CAPI.md b/mlir/docs/CAPI.md
index baba959..73f053d 100644
--- a/mlir/docs/CAPI.md
+++ b/mlir/docs/CAPI.md
@@ -89,8 +89,11 @@
For indexed components, the following pair of functions is provided.
-- `unsigned mlirXGetNum<Y>s(MlirX)` returns the upper bound on the index.
-- `MlirY mlirXGet<Y>(MlirX, unsigned pos)` returns 'pos'-th subobject.
+- `intptr_t mlirXGetNum<Y>s(MlirX)` returns the upper bound on the index.
+- `MlirY mlirXGet<Y>(MlirX, intptr_t pos)` returns 'pos'-th subobject.
+
+The sizes are accepted and returned as signed pointer-sized integers, i.e.
+`intptr_t`. This typedef is avalable in C99.
Note that the name of subobject in the function does not necessarily match the
type of the subobject. For example, `mlirOperationGetOperand` returns a
