[llvm] [LoongArch] Insert nops and emit align reloc when handle alignment directive (PR #72962)

[Jinyang He via llvm-commits]

MQ-mengqing wrote:

Based on psABI v2.30 [1]. In LoongArch psABI v2.30, `R_LARCH_ALIGN` requires symbol index. The lowest 8 bits of addend represent alignment and the other bits of addend represent the maximum number of bytes to emit. The symbol is created by `createTempSymbol()` which calls `createSymbol()` with `CanBeUnnamed` is `true`. And the symbols is in the same section of alignment directive.

[1] https://github.com/loongson/la-abi-specs/blob/release/laelf.adoc


https://github.com/llvm/llvm-project/pull/72962