Auto merge of #1373 - gnzlbg:cleanup_emscripten, r=gnzlbg

.travis.yml

ci/docker/wasm32-unknown-emscripten/Dockerfile

ci/emscripten-entry.sh

ci/emscripten.sh

libc-test/build.rs

libc-test/test/linux_elf.rs

libc-test/test/linux_fcntl.rs

libc-test/test/linux_ipv6.rs

libc-test/test/linux_strerror_r.rs

libc-test/test/linux_termios.rs

src/unix/notbsd/android/mod.rs

src/unix/notbsd/emscripten/mod.rs

src/unix/notbsd/linux/mod.rs

src/unix/notbsd/mod.rs