Fix ununitailzed value_ in LexToken (#530)
Fix ununitailzed value_ in LexToken (#530)

This fixes an uninitialized warning/error when compiling with c++ 7.1.1.
WebAssembly/sexpr-wasm-prototype,WebAssembly/wabt,WebAssembly/sexpr-wasm-prototype,WebAssembly/sexpr-wasm-prototype,WebAssembly/sexpr-wasm-prototype,WebAssembly/wabt,WebAssembly/wabt,WebAssembly/sexpr-wasm-prototype,WebAssembly/sexpr-wasm-prototype,WebAssembly/wabt,WebAssembly/wabt