fix CMakeLists.txt for sanitizer builds
fix CMakeLists.txt for sanitizer builds

This adds the targets all-{asan,lsan,msan}.

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