Added BPositionIO::GetSize() and implemented it by means of Seek() and

Position(). This used up a virtual slot of BPositionIO. GetSize() needed to be
implemented in BFile, which uses the BStatable version as before. This should
hopefully be binary compatible. The only problem could be in source
compatibility when there are classes inheriting from BPositionIO implementing
their own GetSize().


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@17593 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/os/storage/File.h

@@ -57,6 +57,7 @@ public:
 	virtual off_t Position() const;
 
 	virtual status_t SetSize(off_t size);
+	virtual	status_t GetSize(off_t* size) const;
 
 	BFile &operator=(const BFile &file);