Move tests/valid/empty_submodule.m to valid_seq.

It contains a submodule, and parallel mmake can cause spurious failures.

Fix the failure of hard_coded/runtime_opt on Windows.

tests/hard_coded/runtime_opt.exp2:
    Alternative expected output for where stdout and stderr are
    interleaved differently.

tests/hard_coded/runtime_opt.m:
    Document what the expected outputs are for.

Fix a bug in compile-time evaluation.

compiler/uint_emu.m:
    Fix the bounds check for valid uint values.

compiler/{int,uint}_emu.m:
    Use integer.two/0 in a few spots.

Minor documentation fix.

doc/reference_manual.texi:
    s/a/an/ in a couple of spots.

Update a comment.

compiler/Mmakefile:
    We also adjust the default stack size for executables with clang
    on Windows.

Fix hlc test failures with GCC 12.

GCC 12 has new warning, -Winfinite-recursion, that is being triggered by six
tests in the directory tests/valid when compiled in high-level C grades. Since
we also enable -Werror, this is causing these test to fail. Fix these failures
by either removing the infinite recursion from them or by disabling the new GCC
warning for the affected test cases.

configure.ac:
tests/DEFNS_FOR_TESTS.in:
    Define a variable whose value is the option for disabling GCC's infinite
    recursion check.

tests/valid/higher_order5.m:
tests/valid/stack_alloc.m:
    Modify these tests so they do not trigger the infinite recursion warning
    in GCC (or Mercury for that matter).

tests/valid/mode_syntax.m:
tests/valid/same_length_2.m:
    Merge these two tests (under the first name) since they both test the same
    thing.  Delete the same_length_2 version.

tests/valid/Mmakefile:
    Conform to the above deletion.

tests/valid/Mercury.options:
    Include DEFNS_FOR_TESTS here so that mmc --make can see it.

    Disable GCC's infinite recursion check for those tests that trigger
    it.

    Shut up a bunch Mercury warnings for the mode_syntax test case that
    are unrelated to what is actually being tested.

Fix more bad configure escaping.

configure.ac:
    As above.

Improve comments.

Fix spelling.

samples/interpreter.m:
    As above.

Fix structure assignment conflicts with global registers test.

configure.ac:
    As above. The test was inadvertently broken when MR_Spy_Point was
    renamed to MR_SpyPoint. However, it would only make a difference for
    anyone still using gcc < 3.