* Optimize the JEP106 list by using __attribute__((packed)) to remove padding. The x86 & x86_64 series support unaligned accesses just fine, after all, and this is not remotely a hot path.
* Optimize several string-related constructs by switching to fixed-length char arrays, which avoids pointers + relocations.
* app/interrupt.c: array of different-length strings, but most of those are lengthy enough for this to be a clear win, especially on x86_64;
* system/usbhcd.c: array of same-length strings;
* tests/tests.h: array of structs containing same-length strings.
* Reduce the size of the list of tests by using a narrower type for the cpu mode, which reduces padding.