`base/runtime`: do not free the original block on a failed heap resize
The default heap allocator freed old_ptr when the underlying allocation
failed (allocated_mem == nil). On the realloc path (heap_resize) the original
block is left intact on failure, and on the copy/fresh path old_ptr has not
been copied or freed yet, so freeing it left the caller holding a dangling
pointer. A [dynamic] array whose resize failed therefore double-freed its
data on the next delete (reported as free(): invalid pointer / use-after-free).
Return .Out_Of_Memory without freeing anything; the caller retains ownership
of the original block.
Fixes#7262
