The libclang based header generator disallows functions that pass structs (or
more generally "record types") by value. While this can be implemented, the
such functions as emitted by the clang_generator never worked.
We should revisit this when we implement support for passing 128-bit integer
types directly, as those will work the same as small structs.
PiperOrigin-RevId: 485522603
Change-Id: Iae8284720da52496d7a48fe3ca3c3c8605e6d19d
4b56d5606d