The -Zgcc-ld=lld flag makes rust use the rust-lld
linker that is distributed as part of rust toolchain.
However, this flag doesn't work on nixos correctly
as
1) rust-lld needs to be patched to have the correct rpath
to find libz.so
2) the bin/gcc-ld/ld.lld wrapper which calls rust-lld also
needs to be patched to use the correct dynamic loader
3) rust-lld doesn't respect NIX_LDFLAGS which contains
the additional search path derived from buildInputs.
The system linkers on nixos are wrapped so that
NIX_LDFLAGS is added as the rpath to the final binary.
Signed-off-by: Mukilan Thiyagarajan <mukilan@igalia.com>
