* std.Mutex API is improved to not have init() deinit(). This API is
designed to support static initialization and does not require any
resource cleanup. This also happens to work around some kind of
stage1 behavior that wasn't letting the new allocator mutex code
get compiled.
* the general purpose allocator now returns a bool from deinit()
which tells if there were any leaks. This value is used by the test
runner to fail the tests if there are any.
* self-hosted compiler is updated to use the general purpose allocator
when not linking against libc.
