Make --warn-inconsistent-pred-order-clauses the default in most directories.

library/LIB_FLAGS.in:
mfilterjavac/MFILTERJAVAC_FLAGS.in:
profiler/PROF_FLAGS.in:
slice/SLICE_FLAGS.in:
ssdb/SSDB_FLAGS.in:
    Specify --warn-inconsistent-pred-order-clauses as a default flag
    in these directories as well.

library/string.m:
    Reorder code to make this module compile cleanly with
    --warn-inconsistent-pred-order-clauses.

    Don't export base_string_to_int_underscore to lexer.m, since
    lexer.m does not use it anymore, and neither does anything else.
    (The export was not publicly documented.)

library/benchmarking.m:
library/bitmap.m:
library/builtin.m:
library/map.m:
library/profiling_builtin.m:
library/rbtree.m:
library/table_builtin.m:
library/uint.m:
profiler/globals.m:
profiler/options.m:
profiler/prof_info.m:
slice/mdice.m:
slice/mslice.m:
slice/mtc_diff.m:
slice/mtc_union.m:
ssdb/ssdb.m:
    Reorder code to make these modules compile cleanly with
    --warn-inconsistent-pred-order-clauses.

library/Mercury.options:
    Specify --no-warn-inconsistent-pred-order-clauses for the modules
    that would still get warnings without this option.

mfilterjavac/MFILTERJAVAC_FLAGS.in

@@ -4,6 +4,7 @@
 --warn-unknown-format-calls
 --warn-non-contiguous-clauses
 --warn-non-contiguous-foreign-procs
+--warn-inconsistent-pred-order-clauses
 --warn-unused-imports
 --warn-insts-with-functors-without-type
 --halt-at-warn