[name]
VixDiskLib_WriteMetadata

[description]
[code]
VixError
VixDiskLib_WriteMetadata(VixDiskLibHandle diskHandle,
                         const char *key,
                         const char *val);
[endcode]

This function updates the virtual disk metadata with the given <key, value> 
pair.

[parameters]
   diskHandle - Handle to an open virtual disk.
   key - Name of the key.
   val - Value of the above key.

[return]
VIX_OK if the function succeeded, otherwise an appropriate VIX error code.

[remarks]
* This function creates a new <key,value> pair if the given key does not exist.
* Virtual disk metadata keys and their values are ANSI strings.

[example]
[code]
   vixError = VixDiskLib_WriteMetadata(disk.Handle(),
                                       appGlobals.metaKey,
                                       appGlobals.metaVal);
[endcode]
