Print version information more succinctly

In the Mercury compiler itself, and in a number of tools we print a version
string on one line,

    $ mmc --version
    Mercury Compiler, version rotd-2013-10-01, configured for x86_64-unknown-linux-gnu
    Copyright (C) 1993-2013 The University of Melbourne

When the version number is sufficiently long, such as for an ROTD release, this
will wrap on 80 column terminals.  This change splits these strings into two
parts: the version and the architecture string.  These can then either be
printed more succinctly on one line

    $ mmc --version
    Mercury Compiler, version rotd-2013-10-01, on x86_64-unknown-linux-gnu
    Copyright (C) 1993-2013 The University of Melbourne

Or when written to a file such as the .c files that mmc generates, can be
written out onto two lines:

    XXX

library/library.m:
    Make the version predicate return two values, one for the version number
    and the other for the architecture name.  This makes it easier to format
    the version information in the various places it is used.

compiler/handle_options.m:
deep_profiler/mdprof_cgi.m:
deep_profiler/mdprof_create_feedback.m:
deep_profiler/mdprof_report_feedback.m:
deep_profiler/mdprof_test.m:
profiler/mercury_profile.m:
    Format this as shown above for the Mercury compiler and other tools.

compiler/c_util.m:
compiler/elds_to_erlang.m:
compiler/export.m:
compiler/fact_table.m:
compiler/llds_out_file.m:
compiler/mlds_to_c.m:
compiler/mlds_to_cs.m:
compiler/mlds_to_java.m:
compiler/mlds_to_managed.m:
compiler/write_deps_file.m:
    Format version information on two lines when it is used in the
    compiler's various output files.