Reducer: Apply --debug to all commands (#4275)
Reducer: Apply --debug to all commands (#4275)

Do so by applying --debug to extraFlags right at the start. That global
is used everywhere already. In particular, this PR removes manually adding
-g in the first diff chunk here, and you can see extraFlags appears there
already on the previous line.
WebAssembly/binaryen,WebAssembly/binaryen,WebAssembly/binaryen,WebAssembly/binaryen,WebAssembly/binaryen