Linker can give addi too big value

E.g. if we want to load address on 0b1111_1111_1111 (relative), the linker would probably give auipc a zero (a ^ (a & 0xfff)) and give addi whole value 0b1111_1111_1111 (a & 0xfff). Unfortunately, addi would treat it as -1. The correct way is to give auipc value 0b1_0000_0000_0000 and set addi to 0b1111_1111_1111 (-1). In total it is 0b1_0000_0000_0000 - 1 = 0b1111_1111_1111.