forward progress holds with simultaneous interrupts

cMIPS/tests/doTests.sh

cMIPS/tests/interrJR_dlySlot.expected

cMIPS/tests/interrJR_dlySlot.s

cMIPS/tests/interr_x2.expected

cMIPS/tests/interr_x2.s

cMIPS/tests/uart_irx.c

cMIPS/tests/uarttx.c

cMIPS/v_rx.sav

cMIPS/vhdl/core.vhd

cMIPS/vhdl/sdram.vhd

cMIPS/vhdl/tb_cMIPS.vhd