Rework debugging check in BReferenceable.

- If a BReferenceable object is deleted with a non-zero reference count,
  we now test to see if the object was allocated on the stack. If so,
  we don't flag a warning if the reference count is currently 1.

src/kits/support/Referenceable.cpp

@@ -27,8 +27,18 @@ BReferenceable::BReferenceable()
 BReferenceable::~BReferenceable()
 {
 #ifdef DEBUG
-	if (fReferenceCount > 1)
-		debugger("Deleted object which still had references.\n");
+	if (fReferenceCount != 0) {
+		// Simple heuristic to test if this object was allocated
+		// on the stack: check if this is within 1KB in either
+		// direction of the current stack address, and the reference
+		// count is 1. If so, we don't flag a warning since that would
+		// imply the object was allocated/destroyed on the stack
+		// without any references being acquired or released.
+		char test;
+		int64 testOffset = (int64)this - (int64)&test;
+		if (testOffset < -1024 || testOffset > 1024 || fReferenceCount != 1)
+			debugger("Deleted referenceable object with non-zero ref count.");
+	}
 #endif
 }