bricks: fix clang warnings

* bricks/brick-hash.h, bricks/brick-shmem.h: here.

bricks/brick-hash.h

@@ -800,7 +800,7 @@ struct Jenkins {
             saw[i] = SpookyHash::Hash32(buf, i, 0);
             if (saw[i] != expected[i])
             {
-                printf("%3d: saw 0x%.8x, expected 0x%.8lx\n", i, saw[i], expected[i]);
+                printf("%3d: saw 0x%.8x, expected 0x%.8lx\n", i, saw[i], (unsigned long) expected[i]);
                 ASSERT( false );
             }
         }

bricks/brick-shmem.h

@@ -369,7 +369,7 @@ protected:
         Node *next;
         Node() {
             read = write = buffer;
-            next = 0;
+            next = nullptr;
         }
     };
 
@@ -393,7 +393,7 @@ public:
     ~Fifo() {
         while ( head != tail ) {
             Node *next = head->next;
-            ASSERT( next != 0 );
+            ASSERT( next != nullptr );
             delete head;
             head = next;
         }