tests: can fake a compiler not grasping "-c -o" -- globally in all tests

tests: can fake a compiler not grasping "-c -o" -- globally in all tests

The ability to easily do so will be quite important in upcoming changes
about C compilation handling and semantics of the 'subdir-objects'
option.  Refer to the extensive discussion about automake bug#13378 for
more details: <http://debbugs.gnu.org/cgi/bugreport.cgi?bug=13378>.

See also commit 'v1.13.1-34-g744cd57' of 2013-01-08, "coverage: compile
rules used "-c -o" also with losing compilers".

* t/ax/cc-no-c-o.in: New, a "C compiler" that chokes when the '-c' and
'-o' options are passed together to it on the command line.
* Makefile.am (t/ax/cc-no-c-o): Generate this script from it.
(noinst_SCRIPTS, CLEANFILES): Add it.
(EXTRA_DIST): Add 't/ax/cc-no-c-o.in'.
(check-cc-no-c-o): New target, runs the whole testsuite with 'cc-no-c-o'
as the C compiler (bot GNU and non-GNU).
* .gitignore: Update.
* t/ccnoco.sh: Use the new script instead of duplicating it.
* t/ccnoco3.sh: Likewise.
* t/ccnoco4.sh: Likewise.
* t/self-check-cc-no-c-o.sh: New testsuite self-check.
* t/list-of-tests.mk: Adjust.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>