MB-47166: Fix undefined behaviour in iterator_functional_test

As identified during testing for AArch64 support,
iterator_functional_test has a number of instances of undefined
behaviour:

1. iterator_functional_test.cc:776:16: runtime error: null pointer passed as argument 1, which is declared to never be null

The test is trying to use memcmp (as used in implementaiton of
TEST_CMP macro on a nullptr). In this case the length should be zero
so just check that explicitly.

2. iterator_functional_test.cc:1206:29: runtime error: load of address 0xffffe75d46f8 with insufficient space for an object of type 'int'

The test is trying to access the 31st element in a 30-element
array. This actually causes the unit-tests to reliably fail on AArch64
- I assume because we end up with a different undefined value compared
to what x86 (normally) sees and hence it ends up failing a chec
on how many iterations have been performed.

Fix the for() loop termination so it doesn't access off the end.

With this patch AArch64 passes all unit tests.

Change-Id: I31184f0fe8c781575c61864cda2bdfc6c3457e1e
Reviewed-on: http://review.couchbase.org/c/forestdb/+/159305
Reviewed-by: James H <[email protected]>
Tested-by: Build Bot <[email protected]>

Author: daverigby

tests/functional/iterator_functional_test.cc

@@ -773,7 +773,7 @@ void iterator_seek_test()
 
     TEST_CMP(rdoc->key, doc[i]->key, rdoc->keylen);
     TEST_CMP(rdoc->meta, doc[i]->meta, rdoc->metalen);
-    TEST_CMP(rdoc->body, doc[i]->body, rdoc->bodylen);
+    TEST_CHK(rdoc->bodylen == 0);
     fdb_doc_free(rdoc);
     rdoc = NULL;
 
@@ -1198,7 +1198,7 @@ void iterator_complete_test(int insert_opt, int delete_opt)
     }
 
     if (mask & 0x100000) {
-        for (i=0;i<n;++i){
+        for (i=0;i<n-1;++i){
             sprintf(key, keystr_mid, (int)i);
             s = fdb_iterator_seek(fit, key, strlen(key)+1, 0x0);
             (void)s;
@@ -1222,7 +1222,7 @@ void iterator_complete_test(int insert_opt, int delete_opt)
     }
 
     if (mask & 0x1000000) {
-        for (i=0;i<n;++i){
+        for (i=0;i<n-1;++i){
             sprintf(key, keystr_mid, (int)i);
             s = fdb_iterator_seek(fit, key, strlen(key)+1, 0x0);
             (void)s;