Enable Musl 1.2.5's new malloc

[alfreb]

It's supposedly faster, but issues were encountered with this enabled during upgrade to 1.2.5. See discussion in #2251.

[MagnusS]

To test with new malloc, remove "--with-malloc=oldmalloc" from:
https://github.com/includeos/IncludeOS/blob/v0.16.0-release/deps/musl/default.nix#L37
and
https://github.com/includeos/IncludeOS/blob/v0.16.0-release/deps/musl-unpatched/default.nix#L20

With malloc-ng, the kernel currently seems to enter a reboot cycle in libc init, here: https://github.com/includeos/IncludeOS/blob/master/src/platform/x86_pc/init_libc.cpp#L178

Control never comes back to kernel_main.

[torgeiru]

I tracked it down to the aux vectors. The AT_RANDOM aux vector is not valid. This results in a crash. The program will also fail later because mmap does not accept certain flags used, I simply disabled the check for flags for a confirmation.

The AT_RANDOM aux vector(s) is used to generate a canary (__stack_chk..) and by a get_random_secret function during mallocng init. The simple solution is to remove any AT_RANDOM vectors, but we should have a randomized canary and secret for robust/secure mallocng.

[torgeiru]

Updating is crucial for better heap integrity checks, reduces silent failure and detects memory corruption.