libroot: Acquire the process heap lock.

Upon further investigation, the global heap lock should actually
not need to be reset, but the process heap lock will.

Change-Id: Id1fd91cc0e7acecd5b4fd76cb82d4ed2ae3900ad
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6777
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

C11: add aligned_alloc()

Change-Id: If648c0e27ed946874d393e8e33a4548b70c8ecdb
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3377
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

Switch back to hoard2 for now.

We'll reconsider rpmalloc when it has less overhead.