14 GOT-indirect addressing

The following example shows how to load an address from the GOT:

1:
  auipc a0, %got_pcrel_hi(msg + 1)
  ld  a0, %pcrel_lo(1b)(a0)

This generates the following instructions and relocations as seen by objdump (for RV64; RV32 will use lw instead of ld):

0000000000000000 \<.text>:
   0: 00000517            auipc a0,0x0
      0: R_RISCV_GOT_HI20 msg+0x1
   4: 00053503            ld  a0,0(a0) # 0 \<.text>
      4: R_RISCV_PCREL_LO12_I .L1