memcheck/tests/leak_cpp_interior might fail because depending on compiler
and arch used the suppression file used doesn't catch some allocations
through the DT_INIT_ARRAY functions.
That memory doesn't actually leak, it gets freed by the
__gnu_cxx::__freeres hook. But since this testcase shows leaks while
running, not after the program ends, it needs to suppress these allocations.
https://bugs.kde.org/show_bug.cgi?id=406360
The bug itself was solved in 3.12 by the addition of __gnu_cxx::__freeres
in the libstdc++ and have valgrind calling it before exit.
However, depending on the version of the libstdc++, the test leak_cpp_interior
was giving different results.
This commit adds some filtering specific to the test, so as to not depend
anymore of the absolute number of bytes leaked, and adds a suppression entry to
ignore the memory allocated by libstdc++.
This allows to have only 2 .exp files, instead of 4 (or worse, if
we would have to handle yet other .exp files depending on the libstdc++
version).
