streams are not implemented in `wit-bindgen` for C bindings

If you try to generate bindings for 0.3.0 for C it fails:

RUST_BACKTRACE=1 wit-bindgen c --autodrop-borrows yes ./wasi-http/wit-0.3.0-draft -w client
thread 'main' panicked at crates/c/src/lib.rs:780:43:
not implemented
stack backtrace:
   0: rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::panic
   3: wit_bindgen_c::push_ty_name
   4: wit_bindgen_c::gen_type_name
   5: wit_bindgen_c::InterfaceGenerator::define_live_types
   6: <wit_bindgen_c::C as wit_bindgen_core::WorldGenerator>::import_interface
   7: wit_bindgen_core::WorldGenerator::generate
   8: wit_bindgen::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

I realize that this is actually a wit-bindgen issue, but I think C bindings should be a blocker for an 0.3.0 release.

Start by reproducing the command against ./wasi-http/wit-0.3.0-draft with the C generator, then inspect crates/c/src/lib.rs around line 780 and the push_ty_name entry point shown in the backtrace. Done means wit-bindgen generates C bindings for the 0.3.0 streams case without the not implemented panic.