This adds support for `--symbolize-operands`, so that local references
are turned back into labels by objdump, which makes it easier to tell
what is going on with a linked object.
When using `--symbolize-operands`, branch target addresses are not
printed, only the referenced symbol is printed, and the address is
elided:
```
# Without --symbolize-operands
0: 04a05263 blez a0, 0x44 <.text+0x44>
...
40: fd1ff06f j 0x10 <.text+0x10>
44: 00000613 li a2, 0x0
# With --symbolize-operands
0: 04a05263 blez a0, <L3>
...
40: fd1ff06f j <L0>
<L3>:
44: 00000613 li a2, 0x0
```
5b4a5cf51f
