[RenderScript] Always create a new allocation ID in CaptureAllocationInit hook

Due to internal reuse of buffers in the RenderScript runtime by the system allocator,
comparing pointers is not a safe way to check whether an allocation is tracked by lldb.
This change updates the lldb RenderScript internal hook callback to properly
identify and remove old allocations that had have an address that is currently
being tracked.

This change also removes the need for `lldb_private::renderscript::LookupAllocation`
to take a `create` flag, as this is now always the case.

Original Author: <dean@codeplay.com>

Subscribers: lldb-commits
llvm-svn: 277613