I hadn't noticed originally but on powerpc64-linux with 3.4.4 RC2 and
with the 3.4 branch, the results for libstdc++-v3 show only one run of
the tests for "unix", not two for "unix/-m32" and "unix/-m64", and the
results are actually for check-abi. The leftover temp files in the
build directory show that the library tests were actually run, just not
reported. I can't tell if they were run for both -m32 and -m64.
On the 4.0 branch, check-abi is not being run (or not reported?) but
the libstdc++ tests are being run and reported for -m32 and -m64 as
expected.
I'm very sorry I didn't notice this earlier.