RISCVAsmBackend::relaxDwarflineAddr: Try special opcode

LoongArch #77728 did better than RISCV.
If the label difference can be resolved (there is no linker-relaxable
fragment in between), we should use the default handling, which utilizes
a shorter special opcode.

GitOrigin-RevId: 281df9e64720c3ab1c5e03d05087d3fab752d459
2 files changed