[mlir] Add missing const * updates in StandardAttributes

[tpopp]

Summary

This add missing updates to the header file that caused linking issues.
Original change at https://reviews.llvm.org/D91740

[GeorgeLyon]

Whoops, thank you for catching this... these must have disappeared when I was fixing MLIR_CAPI_EXPORTED-related merge conflicts

[tpopp]

No problem :) It's just unfortunate there weren't any tests using this to catch this.

mlir/include/mlir-c/StandardAttributes.h

 /// Checks whether the given attribute is a dense elements attribute.
 MLIR_CAPI_EXPORTED int mlirAttributeIsADenseElements(MlirAttribute attr);
 MLIR_CAPI_EXPORTED int mlirAttributeIsADenseIntElements(MlirAttribute attr);
 MLIR_CAPI_EXPORTED int mlirAttributeIsADenseFPElements(MlirAttribute attr);
 
 /** Creates a dense elements attribute with the given Shaped type and elements
  * in the same context as the type. */
 MLIR_CAPI_EXPORTED MlirAttribute mlirDenseElementsAttrGet(
-    MlirType shapedType, intptr_t numElements, MlirAttribute *elements);
+    MlirType shapedType, intptr_t numElements, MlirAttribute const *elements);
 
 /** Creates a dense elements attribute with the given Shaped type containing a
  * single replicated element (splat). */
 MLIR_CAPI_EXPORTED MlirAttribute
 mlirDenseElementsAttrSplatGet(MlirType shapedType, MlirAttribute element);
 MLIR_CAPI_EXPORTED MlirAttribute
 mlirDenseElementsAttrBoolSplatGet(MlirType shapedType, int element);
 MLIR_CAPI_EXPORTED MlirAttribute

 MLIR_CAPI_EXPORTED MlirAttribute mlirDenseElementsAttrDoubleGet(
     MlirType shapedType, intptr_t numElements, const double *elements);
 
 /** Creates a dense elements attribute with the given shaped type from string
  * elements. The strings need not be null-terminated and their lengths are
  * provided as a separate argument co-indexed with the strs argument. */
 MLIR_CAPI_EXPORTED MlirAttribute
 mlirDenseElementsAttrStringGet(MlirType shapedType, intptr_t numElements,
-                               intptr_t *strLengths, const char **strs);
+                               intptr_t const *strLengths, const char **strs);
 /** Creates a dense elements attribute that has the same data as the given dense
  * elements attribute and a different shaped type. The new type must have the
  * same total number of elements. */
 MLIR_CAPI_EXPORTED MlirAttribute
 mlirDenseElementsAttrReshapeGet(MlirAttribute attr, MlirType shapedType);
 
 /** Checks whether the given dense elements attribute contains a single
  * replicated value (splat). */