Fix nix dev

[cydparser]

I was unable to build c2rust and c2rust-refactor without modifying the flake. This change increases LLVM tools to v19.

[kkysen]

@Rua, would you like to review since I know you use Nix?

[Rua]

c2rust itself builds fine, but running the unit tests (scripts/test_translator.py tests/unit) I get a failure because the quadmath library can't be found:

warning: clang: warning: -lgfortran: 'linker' input unused [-Wunused-command-line-argument]
warning: clang: warning: -lquadmath: 'linker' input unused [-Wunused-command-line-argument]
warning: In file included from src/f128.c:1:
warning: In file included from /nix/store/74qjr01q87nwfl0dbsr1s45p8crw3q1f-glibc-2.40-66-dev/include/stdio.h:28:
warning: In file included from /nix/store/74qjr01q87nwfl0dbsr1s45p8crw3q1f-glibc-2.40-66-dev/include/bits/libc-header-start.h:33:
warning: /nix/store/74qjr01q87nwfl0dbsr1s45p8crw3q1f-glibc-2.40-66-dev/include/features.h:422:4: warning: _FORTIFY_SOURCE requires compiling with optimization (-O) [-W#warnings]
warning: 422 | # warning _FORTIFY_SOURCE requires compiling with optimization (-O)
warning: | ^
warning: src/f128.c:2:10: fatal error: 'quadmath.h' file not found
warning: 2 | #include <quadmath.h>
warning: | ^~~~~~~~~~~~
warning: 1 warning and 1 error generated.

error: failed to run custom build command for f128_internal v0.2.2

[cydparser]

I've added an additional dependency that was needed for cargo test, and removed the stdenv override. @Rua, please reload the dev env and try again.

[Rua]

test_translator.py now runs properly, thanks! cargo test does not, but that wasn't working before with me on Nix, so that's not your fault I think.