Enumerate tests with special rules in tests-special variable.

This patch is a revised and updated version of
<https://sourceware.org/ml/libc-alpha/2014-01/msg00196.html>.

In order to generate overall summaries of the results of all tests in
the glibc testsuite, we need to identify and concatenate the files
with the results of individual tests.

Tomas Dohnalek's patch used $(common-objpfx)*/*.test-result for this.
However, the normal glibc approach is explicit enumeration of the
expected set of files with a given property, rather than all files
matching some pattern like that.  Furthermore, we would like to be
able to mark tests as UNRESOLVED if the file with their results is for
some reason missing, and in future we would like to be able to mark
tests as UNSUPPORTED if they are disabled for a particular
configuration (rather than simply having them missing from the list of
tests as at present).  Such handling of tests that were not run or did
not record results requires an explicit enumeration of tests.

For the tests following the default makefile rules, $(tests) (and
$(xtests)) provides such an enumeration.  Others, however, are added
directly as dependencies of the "tests" and "xtests" makefile
targets.  This patch changes the makefiles to put them in variables
tests-special and xtests-special, with appropriate dependencies on the
tests listed there then being added centrally.

Those variables are used in Rules and so need to be set before Rules
is included in a subdirectory makefile, which is often earlier in the
makefile than the dependencies were present before.  We previously
discussed the question of where to include Rules; see the question at
<https://sourceware.org/ml/libc-alpha/2012-11/msg00798.html>, and a
discussion in
<https://sourceware.org/ml/libc-alpha/2013-01/msg00337.html> of why
Rules is included early rather than late in subdirectory makefiles.

It was necessary to avoid an indirection through the check-abi target
and get the check-abi-* targets for individual libraries into the
tests-special variable.  The intl/ test $(objpfx)tst-gettext.out,
previously built only because of dependencies from other tests, was
also added to tests-special for the same reason.

The entries in tests-special are the full makefile targets, complete
with $(objpfx) and .out.  If a future change causes tests to be named
consistently with a .out suffix, this can be changed to include just
the path relative to $(objpfx), without .out.

Tested x86_64, including that the same set of files is generated in
the build directory by a build and testsuite run both before and after
the patch (except for changes to the
elf/tst-null-argv.debug.out.<number> file name), and a build with
run-built-tests=no to verify there aren't any more obvious instances
of the issue Marcus Shawcroft reported with a previous version in
<https://sourceware.org/ml/libc-alpha/2014-01/msg00462.html>.

	* Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	(tests): Depend on $(tests-special).
	* Makerules (check-abi-list): New variable.
	(check-abi): Depend on $(check-abi-list).
	[$(subdir) = elf] (tests-special): Add
	$(objpfx)check-abi-libc.out.
	[$(build-shared) = yes && subdir] (tests-special): Add
	$(check-abi-list).
	[$(build-shared) = yes && subdir] (tests): Do not depend on
	check-abi.
	* Rules (tests): Depend on $(tests-special).
	(xtests): Depend on $(xtests-special).
	* catgets/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	* conform/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	* elf/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	* grp/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	* iconv/Makefile (xtests): Change dependencies to ....
	(xtests-special): ... additions to this variable.
	* iconvdata/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	* intl/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.  Also add
	$(objpfx)tst-gettext.out.
	* io/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	* libio/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	* malloc/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	* misc/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	* nptl/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	* nptl_db/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	* posix/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	(xtests): Change dependencies to ....
	(xtests-special): ... additions to this variable.
	* resolv/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	(xtests): Change dependencies to ....
	(xtests-special): ... additions to this variable.
	* stdio-common/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	(do-tst-unbputc): Remove target.
	(do-tst-printf): Likewise.
	* stdlib/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	* string/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.
	* sysdeps/x86/Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.

localedata:
	* Makefile (tests): Change dependencies to ....
	(tests-special): ... additions to this variable.