Cleans up a couple of MSVC warnings in testhdf5 (#475)

* Fixes a few testhdf5 warnings raised in Visual Studio

Visual Studio is grumpier about treating pointers like integers than
gcc.

* Committing clang-format changes

Co-authored-by: github-actions <41898282+github-actions[bot]@users.noreply.github.com>

test/trefstr.c

@@ -265,7 +265,9 @@ test_refstr_wrap(void)
     /* Get pointer to raw string in ref-counted string */
     s = H5RS_get_str(rs);
     CHECK_PTR(s, "H5RS_get_str");
-    CHECK(s, buf, "wrapping");
+    if (s == buf)
+        TestErrPrintf("%d: Should not have gotten the same pointer from reference-counted string!\n",
+                      __LINE__);
     cmp = HDstrcmp(s, buf);
     if (cmp <= 0)
         TestErrPrintf("%d: string comparison incorrect!\n", __LINE__);
@@ -375,7 +377,7 @@ test_refstr_acat(void)
 
     /* Append a large string to ref-counted string */
     large_str = HDmalloc(1024);
-    CHECK(large_str, NULL, "HDmalloc");
+    CHECK_PTR(large_str, "HDmalloc");
     HDmemset(large_str, 'a', 1024);
     large_str[1023] = '\0';
     ret             = H5RS_acat(rs, large_str);
@@ -386,7 +388,7 @@ test_refstr_acat(void)
     CHECK_PTR(s, "H5RS_get_str");
     HDsprintf(buf, "%s", "foobar");
     large_str2 = HDmalloc(1024 + 6);
-    CHECK(large_str2, NULL, "HDmalloc");
+    CHECK_PTR(large_str2, "HDmalloc");
     HDstrcpy(large_str2, "foobar");
     HDmemset(&large_str2[6], 'a', 1024);
     large_str2[1029] = '\0';

test/tselect.c

@@ -5381,9 +5381,9 @@ test_select_hyper_union_3d(void)
 
     /* Allocate write & read buffers */
     wbuf = (uint8_t *)HDmalloc(sizeof(uint8_t) * SPACE4_DIM1 * SPACE4_DIM2 * SPACE4_DIM3);
-    CHECK(wbuf, NULL, "HDmalloc");
+    CHECK_PTR(wbuf, "HDmalloc");
     rbuf = (uint8_t *)HDcalloc(sizeof(uint8_t), SPACE3_DIM1 * SPACE3_DIM2);
-    CHECK(rbuf, NULL, "HDcalloc");
+    CHECK_PTR(rbuf, "HDcalloc");
 
     /* Initialize write buffer */
     for (i = 0, tbuf = wbuf; i < SPACE4_DIM1; i++)