lang/rust build fails when converters/libiconv installed on darwin pkgsrc-2023Q4

[S Cole <scole%sdf.org@localhost>]

rust-1.73.0 wouldn't build for me on darwin unless I pkg_delete'd
libiconv first.  The command line args are very long, hopefully I've
attached enough info.  It seemed to fail when linking "cargo".

I believe I'm updated to the most current mac os and Xcode:
Darwin juju.local 23.2.0 Darwin Kernel Version 23.2.0: Wed Nov 15 21:54:10 PST 2023; root:xnu-10002.61.3~2/RELEASE_X86_64 x86_64

[snipped...]
  = note: ld: warning: ignoring duplicate libraries: '-liconv'
          ld: warning: no platform load command found in '/private/var/folders/7d/8z1hkqq546v3jf7cksxnk4tw0000z8/T/rustcbgadfi/symbols.o', assuming: macOS
          ld: Undefined symbols:
            _iconv, referenced from:
                _git_fs_path_iconv in liblibgit2_sys-a7b6993e52e59182.rlib[114](fs_path.o)
            _iconv_close, referenced from:
                _git_fs_path_direach in liblibgit2_sys-a7b6993e52e59182.rlib[114](fs_path.o)
                _git_fs_path_iconv_clear in liblibgit2_sys-a7b6993e52e59182.rlib[114](fs_path.o)
                _git_fs_path_diriter_free in liblibgit2_sys-a7b6993e52e59182.rlib[114](fs_path.o)
                _git_fs_path_dirload in liblibgit2_sys-a7b6993e52e59182.rlib[114](fs_path.o)
            _iconv_open, referenced from:
                _git_fs_path_direach in liblibgit2_sys-a7b6993e52e59182.rlib[114](fs_path.o)
                _git_fs_path_iconv_init_precompose in liblibgit2_sys-a7b6993e52e59182.rlib[114](fs_path.o)
                _git_fs_path_diriter_init in liblibgit2_sys-a7b6993e52e59182.rlib[114](fs_path.o)
          clang: error: linker command failed with exit code 1 (use -v to see invocation)
          

[snipped...]
error: could not compile `cargo` (bin "cargo") due to previous error

Traceback (most recent call last):
  File "/Users/scole/pkgsrc/lang/rust/work/rustc-1.73.0-src/./x.py", line 50, in <module>
    bootstrap.main()
  File "/Users/scole/pkgsrc/lang/rust/work/rustc-1.73.0-src/src/bootstrap/bootstrap.py", line 1121, in main
    bootstrap(args)
  File "/Users/scole/pkgsrc/lang/rust/work/rustc-1.73.0-src/src/bootstrap/bootstrap.py", line 1096, in bootstrap
    run(args, env=env, verbose=build.verbose, is_bootstrap=True)
  File "/Users/scole/pkgsrc/lang/rust/work/rustc-1.73.0-src/src/bootstrap/bootstrap.py", line 184, in run
    raise RuntimeError(err)
RuntimeError: failed to run: /Users/scole/pkgsrc/lang/rust/work/rustc-1.73.0-src/build/bootstrap/debug/bootstrap -v build --stage 2 -j 1
*** Error code 1

Stop.
bmake[8]: stopped in /Users/scole/pkgsrc/lang/rust
*** Error code 1

Thanks