This patch starts the process of generating explicit PASS or FAIL
status for individual glibc tests. It's based on Tomas Dohnalek's
patch <https://sourceware.org/ml/libc-alpha/2012-10/msg00278.html>,
but is deliberately more minimal: it doesn't try to cover any tests
outside of $(tests) / $(xtests) (that's done in patch 2), nor does it
put the result together in an overall summary file (patch 5): it just
generates the .test-result files.
Thus, this patch keeps the overall logic for when a testsuite run
finishes completely unchanged: a test failing will terminate the run.
I think we *should* move to a more conventional approach where plain
"make check" does not terminate for an individual test failure, unless
e.g. you say "make stop-on-test-failure=y check", but that sort of
policy change is best done as a separate patch (patch 6) once the
infrastructure is in place to generate summary files for completed
test runs (which will entirely consist of PASS and XFAIL lines if the
testsuite run reaches the point of generating them, until such a
policy change is made).