Fix Bug in GC Reallocation Calculation
Fix Bug in GC Reallocation Calculation

Updates the way we calculate thenext GC to make sure that we're not
already past the threshold. This was causing endless garbage collections
on 32 bit builds in `test/language/deeply_nested_gc.wren`.

minirop/wren,Nelarius/wren,foresterre/wren,munificent/wren,minirop/wren,foresterre/wren,Nelarius/wren,munificent/wren,Nelarius/wren,minirop/wren,minirop/wren,munificent/wren,Nelarius/wren,minirop/wren,foresterre/wren,foresterre/wren,Nelarius/wren,foresterre/wren,munificent/wren,munificent/wren,munificent/wren