- `fcntl` was renamed to `fcntl64` in glibc 2.28 (see #9485)
- `res_{,n}{search,query,querydomain}` became "their own" symbols since
glibc 2.34: they were prefixed with `__` before.
This PR makes it possible to use `fcntl` with glibc 2.27 or older and
the `res_*` functions with glibc 2.33 or older.
These patches will become redundant with universal-headers and can be
dropped. But we have to do with what we have now.
Closes#9485
This commit introduces tools/update_glibc.zig to update the start files
for next time.
Some notable changes in recent glibc:
* abi-note.S has been changed to abi-note.c but we resist the change to
keep it easier to compile the start files.
* elf-init.c has been deleted upstream. Further testing should be done
to verify that binaries against glibc omitting elf-init.c still run
properly on oldel glibc linux systems.
Closes#4926
