WIP: Elf64 shlib cleanup

modified:   file.cpp
	modified:   file.h
	modified:   p_elf_enum.h
	modified:   p_lx_elf.cpp
	modified:   p_lx_elf.h

src/file.h

@@ -143,6 +143,7 @@ public:
 
     // FIXME - these won't work when using the '--stdout' option
     virtual upx_off_t seek(upx_off_t off, int whence) override;
+    virtual upx_off_t tell() const;
     virtual void rewrite(const void *buf, int len);
 
     // util