Use INTERNAL_MEM_SIZE to define cpu.mem{8,16,32}
Use INTERNAL_MEM_SIZE to define cpu.mem{8,16,32}

Since INTERNAL_MEM_SIZE is a variable we'll need to keep in sync between
global_pointers.h (WASM) and const.js (JS), doing this lets it be more obvious
when they fall out of sync. (If only starter.js used it, our WASM memory would
merely be smaller than required and we'd only find out when we tried to access it
out of bounds.)

copy/v86,copy/v86,copy/v86,copy/v86,copy/v86,copy/v86,copy/v86