AcquireReference() now returns the previous ref count.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@42079 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/shared/Referenceable.h

@@ -17,7 +17,7 @@ public:
 								BReferenceable();
 	virtual						~BReferenceable();
 
-			void				AcquireReference();
+			int32				AcquireReference();
 			bool				ReleaseReference();
 									// returns true after last
 

src/kits/support/Referenceable.cpp

@@ -28,13 +28,16 @@ BReferenceable::~BReferenceable()
 }
 
 
-void
+int32
 BReferenceable::AcquireReference()
 {
-	if (atomic_add(&fReferenceCount, 1) == 0)
+	int32 previousReferenceCount = atomic_add(&fReferenceCount, 1);
+	if (previousReferenceCount == 0)
 		FirstReferenceAcquired();
 
 	TRACE("%p: acquire %ld\n", this, fReferenceCount);
+
+	return previousReferenceCount;
 }