Revisit valgrind suppressions

[pinepain]

At the moment some valgrind reports which doesn't look like relevant one to project, one which comes from v8 internals and other which happens only in docker, are suppressed (see #47 for details).

Ideally they should be revisited and validated.

[pinepain]

To workaround missed debug info in library (https://bugs.chromium.org/p/chromium/issues/detail?id=603286) we have add more valgrind overrides for the same false-positive reporting.

[pinepain]

It came up that the issue was in how I built libv8: it was built with clang and in general was not build to be relocatable, so the fact that libv8 worked was more a coincidence then by design.

Starting from libv8 6.5.116 I build it with the following GN args:

    is_debug: false,
    is_official_build: true,
    is_component_build: true,
    is_cfi: false,
    is_clang: false,
    v8_use_external_startup_data: false,
    treat_warnings_as_errors: false,
    use_custom_libcxx: false,
    use_sysroot: false,
    use_gold: false

which fits packaging needs much better and for now tests shows that memory issue reports gone.