riscv64: fix filtering of consecutive AUIPC

	modified:   src/filter/auipc.h
	modified:   src/stub/riscv64-linux.elf-fold.h
	modified:   src/stub/riscv64-linux.elf-so_fold.h
	modified:   src/stub/src/arch/riscv/64/bxx.S
	modified:   src/stub/src/riscv64-linux.elf-fold.S