vpSetClientData - define a client data pointer
vpc VolPack context from vpCreateContext.
Pointer to application-specific client data.
vpSetClientData is used to store a pointer to application-specific
client data in the VolPack context. This pointer is passed to some of
the callback routines (see vpSetCallback(3)) to allow the application
to define its own state variables. The pointer is not used by VolPack.
The return value is always VP_OK.
VolPack(3), vpCreateContext(3), vpSetCallback(3)