Add test kernel that uses SSE feature

[phil-opp]

We currently only test the bootloader without the SSE feature. We should add an additional test kernel that makes use of it.

[GuillaumeDIDIER]

It may depend on optimization level, but a kernel that has +mmx, +sse enable, opt level 0 and calls panic!() appears to end up having some nice SSE instruction used to do some tuple unpacking/repacking in panic. Adding to that some reasonable float code can probably turn into a nice sanity check.