Log Message:
mold: update to 0.9.5.

Highlights of mold 0.9.5:

- In 0.9.4, we changed the mold's behavior on remaining weak undefined
  symbols, so that they would be resolved to address zero if we were
  creating a shared object file with the -z defs option. Now, such symbols
  will be promoted to dynamic symbols so that they'll get another chance
  to be resolved at run-time. This change fixes a regression of Firefox
  build failure (#114), which depends on this particular linker behavior
  to export symbols from libxul.so.
- mold can now be built on macOS. Note that mold is still able to produce
  only ELF (Unix) files — so you can use it for cross compilation on
  macOS for Linux, but you can't use mold for macOS native development.
- Relocation overflow are now reported as errors on AArch64 and
  i386. Previously, such relocations were silently producing incorrect
  output.

Highlights of mold 0.9.4:

- mold -run now intercepts invocations of ld, ld.lld and ld.gold wherever
  they are in the directory hierarchy. Previously, they were intercepted
  only if they were in /usr/bin. This change was made because it is not
  uncommon to install a compiler toolchain into a directory other than
  the system bin directory.
- AArch64 (Arm 64-bit) support has been significantly improved. mold
  can now link many real-world programs including itself for AArch64.
- Fix an issue that relocation addends were not handled correctly
  for i386.
- mold is now able to link LLVM compiler-rt's CRT files.
- Fix an issue that a dynamic relocation was created for a read-only
  section if the relocation refers an unresolved weak symbol.
- Undefined weak symbols are now always resolved to address 0 instead
  of being promoted to dynamic symbols.