coll/han: fix compiler warnings

Fix an unused variable, and explictly cast uint64_t to size_t

Note that the latter won't be needed after embiggening collectives for large count support.

Signed-off-by: Wenduo Wang <wenduwan@amazon.com>

Author: wenduwan

ompi/mca/coll/han/coll_han.h

@@ -522,7 +522,7 @@ ompi_coll_han_reorder_gather(const void *sbuf,
                              int * topo);
 
 size_t
-coll_han_utils_gcd(const size_t *numerators, const size_t size);
+coll_han_utils_gcd(const uint64_t *numerators, const size_t size);
 
 int
 coll_han_utils_create_contiguous_datatype(size_t count, const ompi_datatype_t *oldType,

ompi/mca/coll/han/coll_han_gatherv.c

@@ -332,7 +332,7 @@ int mca_coll_han_gatherv_intra(const void *sbuf, int scount, struct ompi_datatyp
     }
 
     if (max_data_size > (size_t) INT_MAX) {
-        datatype_size = coll_han_utils_gcd((const size_t *) low_data_size, low_size);
+        datatype_size = coll_han_utils_gcd(low_data_size, low_size);
     }
 
     low_rcounts = malloc(low_size * sizeof(int));

ompi/mca/coll/han/coll_han_scatterv.c

@@ -343,7 +343,7 @@ int mca_coll_han_scatterv_intra(const void *sbuf, const int *scounts, const int
     }
 
     if (max_data_size > (size_t) INT_MAX) {
-        datatype_size = coll_han_utils_gcd((const size_t *) low_data_size, low_size);
+        datatype_size = coll_han_utils_gcd(low_data_size, low_size);
     }
 
     low_scounts = malloc(low_size * sizeof(int));

ompi/mca/coll/han/coll_han_utils.c

@@ -25,12 +25,12 @@
  * @param[in]   size            Number of numerators
  * @returns     The GCD, where 1 <= GCD
  */
-size_t coll_han_utils_gcd(const size_t *numerators, const size_t size)
+size_t coll_han_utils_gcd(const uint64_t *numerators, const size_t size)
 {
-    size_t denominator = numerators[0], numerator, tmp;
+    size_t denominator = (size_t) numerators[0], numerator, tmp;
 
     for (size_t i = 1; i < size; ++i) {
-        numerator = numerators[i];
+        numerator = (size_t) numerators[i];
 
         if (0 == denominator) {
             denominator = numerator;