s3:param: alloc lp_load_ex() to take an existing 'FILE *' pointer instead of a path

s3:param: alloc lp_load_ex() to take an existing 'FILE *' pointer instead of a path

This will be useful in order to use open_memstream()/fmemopen() in order
to create a deep copy of an s4 lpctx into an s3 context without having
an existing smb.conf file on disk.

Signed-off-by: Stefan Metzmacher <metze@samba.org>