[m-dev.] inefficiencies when creating the .opt file

[Christopher Rodd SPEIRS]

> Estimated hours taken: 3
> 
> Efficiency improvements for inter-module optimization.
> 
> compiler/intermod.m
> compiler/mercury_compile.m
> 	Fix a bug with the date-stamps and --intermod-unused-args by
> 	delaying calling update_interface and touch_interface_datestamp
> 	until after the unused arguments information has been written to
> 	the .opt.tmp file.
> 
> compiler/unused_args.m
> 	Write unused argument information to the .opt.tmp file rather 
> 	than the .opt file.
> 
> compiler/dead_proc_elim.m
> compiler/mercury_compile.m
> 	Add a pass to eliminated dead non-local predicates immediately after 
> 	building the HLDS to avoid doing analysis of predicates from .opt 
> 	files which are not used.
> 
> compiler/hlds_module.m
> 	Add module_info_remove_predicate to remove a predicate completely from
> 	the predicate_table.
> 

That looks fine thanks Simon



Chris