The Hunk error was definitely my fault. I clearly didn't do the diff on the original. Sorry about that.
I think you're spot on, about it being Qt5 related, though. I fired up some old hardware (no sse2) and was able to compile 0.7.2 without the SSE2 instructions in xerces just fine, but gdb reveals that the illegal instruction error had then moved from Sigil to libQt5Webkit.
Looks like the only option left to you would be to compile Qt5 yourself on that hardware.
Last edited by DiapDealer; 04-24-2013 at 04:46 PM.