libc, kernel: import more functions from musl

Signed-off-by: Paweł Dziepak <pdziepak@quarnos.org>
kernel: minor panic() changes

Signed-off-by: Paweł Dziepak <pdziepak@quarnos.org>
libc: use stubbed locale support

Proper locale support is not important in the kernel and, at least at
the moment, is creating more problems than it is worth.

Signed-off-by: Paweł Dziepak <pdziepak@quarnos.org>
arch/x64, kernel: read memory map, add early memory allocator

Signed-off-by: Paweł Dziepak <pdziepak@quarnos.org>
arch/x64: add support for tls

Signed-off-by: Paweł Dziepak <pdziepak@quarnos.org>