Defer Cargo links metadata printing until after code generation
Defer Cargo links metadata printing until after code generation

This results in slightly less noise when code generation produces an
error during a Cargo build.

Before:

    process didn't exit successfully: `/git/example-cxx/target/debug/build/example-f20ef12178a95a23/build-script-build` (exit code: 1)
    --- stdout
    cargo:CXXBRIDGE_PREFIX=example
    cargo:CXXBRIDGE_DIR0=/git/example-cxx/target/debug/build/example-188c8410ffc8bb7d/out/cxxbridge/include
    cargo:CXXBRIDGE_DIR1=/git/example-cxx/target/debug/build/example-188c8410ffc8bb7d/out/cxxbridge/crate

    --- stderr

    error[cxxbridge]: extern type with lifetimes is not supported yet
      ┌─ src/main.rs:9:21
      │
    9 │         type Object<'a>;
      │                     ^^ extern type with lifetimes is not supported yet

After:

    process didn't exit successfully: `/git/example-cxx/target/debug/build/example-f20ef12178a95a23/build-script-build` (exit code: 1)
    --- stderr

    error[cxxbridge]: extern type with lifetimes is not supported yet
      ┌─ src/main.rs:9:21
      │
    9 │         type Object<'a>;
      │                     ^^ extern type with lifetimes is not supported yet

dtolnay/cxx,dtolnay/cxx,dtolnay/cxx,dtolnay/cxx