Returns a the number of enabled library handling extensions.
ERROR: Syntax information about ILibraryLookupInfo.ExtensionCount may not be in D:\ArcGIS\DotNet\ESRI.ArcGIS.SystemUtility.dll
[C++]
HRESULT ExtensionCount(
long* lCount
);
[C++]Parameters
lCount [out, retval] lCount is a parameter of type long