Format test results closer to what DejaGnu does

The years of dealing with Binutils, GCC and GDB test results
made the community create good tools for comparison and analysis
of DejaGnu test results.  This change allows to use those tools
for Glibc's test results as well.

The motivation for this change is Linaro's pre-commit testers,
which use a modified version of GCC's validate_failures.py
to create test xfail lists with baseline failures and known
flaky tests.  See below links for an example xfails file (only
one link is supposed to work at any given time):
- https://ci.linaro.org/job/tcwg_glibc_check--master-arm-build/lastSuccessfulBuild/artifact/artifacts/artifacts.precommit/sumfiles/xfails.xfail/*view*/
- https://ci.linaro.org/job/tcwg_glibc_check--master-arm-build/lastSuccessfulBuild/artifact/artifacts/sumfiles/xfails.xfail/*view*/



Specifacally, this patch changes format of glibc's .sum files from ...
<cut>
FAIL: elf/test1
PASS: string/test2
</cut>
... to ...
<cut>
             === glibc tests ===

Running elf ...
FAIL: elf/test1

Running string ...
PASS: string/test2
</cut>.

And output of "make check" from ...
<cut>
FAIL: elf/test1
</cut>
... to ...
<cut>
FAIL: elf/test1
		=== Summary of results ===
      1 FAIL
      1 PASS
</cut>.

Signed-off-by: Maxim Kuvyrkov <maxim.kuvyrkov@linaro.org>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>