Allocate large numbers of huge BigIntegers in rapid succession. Most of the
associated memory will be in the C++ heap. This makes sure that we trigger
the garbage collector often enough to prevent us from running out of memory.

The test allocates roughly 10GB of native memory, approximately 1MB of which
will be live at any point. Basically all native memory deallocation is
triggered by Java garbage collection.

This test is a lot nastier than it looks. In particular, failure on target tends
to exhaust device memory, and kill off all processes on the device, including the
adb daemon :-( .
