s3-param: Rename loadparm_s3_context -> loadparm_s3_helpers

s3-param: Rename loadparm_s3_context -> loadparm_s3_helpers

This helps clarify the role of this structure and wrapper function.

The purpose here is to provide helper functions to the lib/param
loadparm_context that point back at the s3 lp_ functions.  This allows
a struct loadparm_context to be passed to any point in the code, and
always refer to the correct loadparm system.  If this has not been
set, the variables loaded in the lib/param code will be returned.

As requested by Michael Adam.

Andrew Bartlett

Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Wed Jun 27 17:11:16 CEST 2012 on sn-devel-104