Fix the behaviour of string.from_char_list in C# and Java grades.

The predicate string.from_char_list and string.from_reverse_char_list should
throw an exception if their input lists contain the null character.  This
was not done for the C# and Java grades for the former, and the C# grade for
the latter.
(This fixes the failure of tests/hard_coded/null_char in the C# grade and
almost fixes it for the Java grade.)

library/string.m:
	Make the above predicates throw an exception if their input lists
	contain the null character.

NEWS:
	Announce the above fix.
Fix a test case failure in the C# grade.

Avoid some warnings during runtests.

tests/hard_coded/write.exp3:
	Update this expected output.

tests/hard_coded/hash_bug.m:
	Do not call an obsolete function.

tests/hard_coded/Mercury.options:
	Do not warn about unresolved polymorphism in a test.
Cleanups for tests/hard_coded.

tests/hard_coded/Mmakefile:
	Only run the target_mlobjs test case in C grades; directly linking
	against an object file isn't possible in the non-C grades.

tests/hard_coded/Mercury.options:
	Suppress irrelevant warnings generated by some tests.

tests/hard_coded/hash_init_bug.m:
	Replace a call to an obsolete function.
Fix the failure of tests/hard_coded/bigtest in the C# grade.

tests/hard_coded/lp.m:
	Add a C# foreign_proc for mkuniq/2.
Fix problems with the Mercury compiler in the C# grade.

Fix some problems that prevent the Mercury compiler building and running in the
C# grade.  "Running" here means that ./mercury_compile --help works; I haven't
tried anything more ambitious (yet).

mdbcomp/shared_utilities.m:
	Add a Mercury definition of unlimit_stack/2 for use by the non-C
	backends.

runtime/mercury.h:
	Do not cause a preprocessor error if we are compiling with high-level
	code and without the Boehm GC if we are using clang.
	We need this on OS X because we include this header when building the
	programs in the util directory and on OS X we will probably be using
	clang rather than GCC.  (Clang and GCC both support the required
	extensions to C here, so this won't be a problem.)
Fix references to ssdb_hooks in C# grades.

The Mono compiler started giving me these errors for references to the
`ssdb_hooks' global from other modules:

Mercury/opts/exception.opt(365,15): error CS0103:
The name `ssdb_hooks' does not exist in the current context

library/exception.m:
	Qualify references to `ssdb_hooks' symbol.
Fix a problem with the runtests target in the C# grade.

Mmake.workspace:
	Don't pass the static archives for the Mercury libraries via --link-object
	(MLOBJS) when building compiler executables and test cases in the C# grade.
	The origin of this setting was (probably) the old il grade; it doesn't
	make sense for the csharp grade however and prevents the test suite from
	working properly in that grade.
More work on running the test suite in non-C grades.

Mmake.workspace:
	Do not set MLOBJS in the java and erlang grades.

tests/warnings/singleton_text.exp[234]:
tests/warnings/warn_succ_ind.exp[234]:
	Update these expected outputs to conform to changes to both the file
	generating the warning and also to the way the Mercury compiler prints
	them.
Merge branch 'version-14_01-branch'