b4c4b28e43
locore calls to go via a locore-entry jumptable. Declare r2000- and r4000-specific exception-handler functions, to which trap() and interrupt() dispatch exceptions. Initialize r2000- and r4000- specific exception-handler vectors, when CPU_R4000 and CPU_R2000 are defined. Update the stack-traceback code (partially) to understand and print the new low-level exception-handler code, via which machine exception-vectors send exceptions to call trap() or interrupt(). This needs more work.