I think I'll just rewrite the signal related stuff in rts-rt0.c, implement some BSD/SYSV independant routines that ONLY mask signals that are actually present on the target system.
I have personally found this feature annoying. I DO want a core dump in the case of a SIGSEGV so I can see where it occured with a debugger. Should the default be not to have it and if you want it have a run time flag or a configure flag that enables by default?