Re: --cpu:avr and standard library

[Araq]

`compiler/platform.nim` contains this line, `(name: "avr", intSize: 16, endian: 
littleEndian, floatSize: 32, bit: 16),` and mapping `int` to a 16bit type is 
not a smart move.  Not sure how to improve that, the memory allocator assumes a 
32bit system anyway. No idea why you expect the GC'ed sequence stuff on an AVR 
either. `--cpu:avr` is for `--os:standalone --gc:none` targets.