Log Message:
mold: update to 1.5.0.

mold 1.5.0 is a new release of the high-speed linker. The highlight of this
release is that we start supporting the following four new targets: PPC64LE,
SPARC64, RV32BE and RV64BE. mold 1.5.0 also includes various bug fixes,
performance and compatibility improvements as shown below.

New features:

- PPC64LE and SPARC64 are now supported as new targets. They haven't yet
  been as well tested as other targets, but they are already able to link
  mold itself on these platforms. (Note that PPC64LE is very unlikely to
  work on the most recent POWER10 machines as we didn't have a chance to
  test it due to a limited availability (POWER10 was released in 2021). If
  you can support us on this matter, please contact us. We also accept
  donations, so please consider supporting our project!)
- RV32BE and RV64BE (32-bit and 64-bit big-endian RISC-V) are now supported
  as experimental targets. RISC-V is usually little-endian, but there exists
  a big-endian RISC-V as an extension. You can make gcc to emit code for
  big-endian RISC-V by passing -mbig-endian. mold can now link object files
  generated with that option.
- --compress-debug-sections=zstd is now supported. This is an option to
  compress debug info embedded to an output file with Zstandard compression
  algorithm. Compared to the existing --compress-debug-sections=zlib, zstd
  is faster and gives a higher compression ratio. You probably can't start
  using zstd compression today though, because other tools such as gdb may
  not be able to read zstd-compressed debug info yet. But adding this option
  early makes mold future-proof.
- mold no longer aligns loadable segments to page boundaries to reduce output
  file size. Previously, we allocated holes between loadable segments. The
  saving by this change is most visible for small programs. For example, a
  "hello world" program used to be ~18 KiB on x86-64. It's now 7.2 KiB.

Bug fixes and compatibility improvements:

- [RISCV] We optimized code so that the link speed for RISC-V is now
  comparable to the other targets. As an example, linking mold itself (~150
  MiB in size) for RV64 used to take ~45 seconds on a simulated 16-core
  machine. It now takes only ~0.25 seconds.
- mold used to create more than one .rodata section under a certain
  condition. It's not technically wrong but confused Valgrind. This issue
  has been resolved.
- [ARM32] Previously, mold failed to promote remaining undefined symbols to
  dynamic symbols if symbols are undefined weak. That caused a link failure
  for libxml. This issue has been resolved.
- mold didn't copy symbol types when creating symbol aliases for the --defsym
  option.

Removed features:

- --compress-debug-sections=zlib-gnu has been removed. LLVM lld removed that
  option too as there seems to be no usage of the flag.