Hmm... I downloaded a fresh copy from your site, replaced the sdl folder with the one containing the new debugger, ran a build and get this when I launching the application:
M.A.M.E. v0.108u4 (Sep 16 2006) - Multiple Arcade Machine Emulator
So it seems to me that I am
running u4 indeed
Edit: oops, I think we misunderstood each other.
./mameg4d pacman --> works fine
./mameg4d -debug pacman --> bus error
Edit 2: works fine on my Intel iMac