py/vm: Remove currently_in_except_block variable.
py/vm: Remove currently_in_except_block variable.

After the previous commit it is no longer needed.

henriknelson/micropython,henriknelson/micropython,pfalcon/micropython,tobbad/micropython,henriknelson/micropython,adafruit/circuitpython,henriknelson/micropython,trezor/micropython,pramasoul/micropython,bvernoux/micropython,pramasoul/micropython,selste/micropython,selste/micropython,pozetroninc/micropython,MrSurly/micropython,selste/micropython,kerneltask/micropython,selste/micropython,adafruit/circuitpython,trezor/micropython,tobbad/micropython,adafruit/circuitpython,bvernoux/micropython,pozetroninc/micropython,pfalcon/micropython,bvernoux/micropython,MrSurly/micropython,selste/micropython,pfalcon/micropython,adafruit/circuitpython,tobbad/micropython,trezor/micropython,kerneltask/micropython,pramasoul/micropython,tobbad/micropython,pramasoul/micropython,kerneltask/micropython,adafruit/circuitpython,pramasoul/micropython,adafruit/circuitpython,MrSurly/micropython,pozetroninc/micropython,pfalcon/micropython,pfalcon/micropython,pozetroninc/micropython,MrSurly/micropython,MrSurly/micropython,kerneltask/micropython,henriknelson/micropython,trezor/micropython,kerneltask/micropython,tobbad/micropython,trezor/micropython,bvernoux/micropython,pozetroninc/micropython,bvernoux/micropython