Add -p option to run-tests.py to show the commands it runs (#379)
Add -p option to run-tests.py to show the commands it runs (#379)

Without this it can be hard to dig down that find out
exactly what is being run

WebAssembly/sexpr-wasm-prototype,WebAssembly/sexpr-wasm-prototype,WebAssembly/sexpr-wasm-prototype,WebAssembly/wabt,WebAssembly/wabt,WebAssembly/wabt,WebAssembly/sexpr-wasm-prototype,WebAssembly/sexpr-wasm-prototype,WebAssembly/sexpr-wasm-prototype,WebAssembly/wabt,WebAssembly/wabt