Add missing printDebug wasm runtime function

[martyall]

I guess this function is now required by the circom runtime as of version 2.2. I discovered this when trying to run and received the following error:

thread 'main' panicked at /home/martyall/.cargo/git/checkouts/circom-compat-f8dd94f015257c55/09e92d4/src/circom/builder.rs:31:61:
called `Result::unwrap()` on an `Err` value: Error while importing "runtime"."printDebug": unknown import. Expected Function(FunctionType { params: [I32], results: [] })

fixes ##78