Remove Windows oneAPI warning for unused function (#4878)

testpar/t_mpi.c

@@ -175,6 +175,8 @@ test_mpio_overlap_writes(char *filename)
 #define GB            1073741824  /* 1024**3 == 2**30 */
 #define TWO_GB_LESS1  2147483647  /* 2**31 - 1 */
 #define FOUR_GB_LESS1 4294967295L /* 2**32 - 1 */
+
+#ifndef H5_HAVE_WIN32_API
 /*
  * Verify that MPI_Offset exceeding 2**31 can be computed correctly.
  * Print any failure as information only, not as an error so that this
@@ -409,6 +411,7 @@ test_mpio_gb_file(char *filename)
         free(buf);
     return (nerrs);
 }
+#endif
 
 /*
  * MPI-IO Test: One writes, Many reads.