boulder/data: Add LLVM CREL tuning flags

[joebonrichie]

https://maskray.me/blog/2024-03-09-a-compact-relocation-format-for-elf

Reduces the size of .o/.a files.

Currently, final executables are unaffected as LLD consumes the crel symbols until support for DT_CREL is added to ABI and GNU toolchain

The primary benefit is reducing size on disk for cached builds

Be aware that ld.bfd cannot handle CREL static .a files.

A simple lzip build:

CREL disabled:
308K arg_parser.o
176K decoder.o
140K encoder_base.o
224K encoder.o
132K fast_encoder.o
112K list.o
248K lzip_index.o
608K main.o

CREL enabled:
264K arg_parser.o
152K decoder.o
120K encoder_base.o
196K encoder.o
116K fast_encoder.o
92K list.o
212K lzip_index.o
520K main.o

[ermo]

This is wild. Sorry I missed it.

Could we link the toolchain commits/PRs to this PR so we know when it makes sense to begin testing with it against glibc/binutils/llvm packages which support CREL?

[joebonrichie]

Waiting on ABI changes to be accepted: https://groups.google.com/g/generic-abi/c/ppkaxtLb0P0

There seems to be not much discussion on the GNU side unfortunately

glibc: https://sourceware.org/bugzilla/show_bug.cgi?format=multiple&id=31541
binutils: https://sourceware.org/bugzilla/show_bug.cgi?id=31475