Log Message:
mold: update to 2.1.0.

New features:

- Loongson's LoongArch CPU has been supported.
- -z nosectionheader has been added to eliminate section headers from the
  output file.

Bug fixes and compatibility improvements:

- Previously, linking with the -z pack-relative-relocs option produces
  an executable that glibc 2.38 refuses to run with DT_RELR without
  GLIBC_ABI_DT_RELR dependency error. Now, mold produces binaries compatible
  with glibc 2.38.
- [ARM64] R_AARCH64_ADR_PREL_PG_HI21_NC relocation type has been supported.
- [ARM64] R_AARCH64_MOVW_UABS_G3 relocation type has now been handled as a
  PLT-generating relocation to fix an issue when main is not defined in the
  main executable but rather in a .so file.
- [RISC-V] We now merge input .riscv.attributes contents. Previously, we
  just concatenated them.