EHN: Use XINDEX to generate routine list for a package

XINDEX routine itself provides the ability to generate routine list
by prefix/namespace. Change the current workflow to utilize that as it
is platform independent and more efficient especially on GT.M platform.

Also clean up the old logic.

OSEHRA-Id: http://issues.osehra.org/browse/OAT-95
Change-Id: Ief22176be6865bdf9dd110782a30c029afbce80e
Merge "EHN: Use XINDEX to generate routine list for a package"