setup-re2.bash: switch to gcc as llvm-gcc was eliminated
setup-re2.bash: switch to gcc as llvm-gcc was eliminated

megahall/sdn_sensor,megahall/sdn_sensor,megahall/sdn_sensor,megahall/sdn_sensor,megahall/sdn_sensor,megahall/sdn_sensor,megahall/sdn_sensor,megahall/sdn_sensor