This patch reflects eventual allocation errors in a more specific way to
the caller of 'alloc_aligned', in particular out-of-metadata and
out-of-memory are considered as different conditions.
Related to issue #526.
The first metadata-block, which is inherent part of the allocator object
itself has a fixed size which isn't suitable enough for some 64bit platforms
(e.g. core's RAM-allocator on a 64bit platform with lots of different regions).
This commit let the block size be address-width aware.
This patch implements the support needed to handle exceptions that occur
during the construction of objects dynamically allocated via the
'Allocator' interface. In this case, the compiler automatically invokes
a special delete operator that takes the allocator type (as supplied to
'new') as second argument. The implementation of this delete operator
has been added to the 'cxx' library. Because the operator delete is
called without the size of the object, we can use only those allocators
that ignore the size argument of the free function and print a warning
otherwise. The added 'Allocator::need_size_for_free()' function is used
to distinguish safe and unsafe allocators.
