Include sanitizer library in build

[kripken]

It would be useful for WebAssembly/binaryen#557 to have the clang from the waterfall be sanitzer-enabled, then we could use it to build on travis. Looks like what's blocking this is that

• libclang_rt.ubsan_standalone-x86_64.a
• libclang_rt.asan-x86_64.a
• libclang_rt.tsan-x86_64.a

are missing, e.g.

/usr/bin/ld: cannot find

  /home/travis/build/WebAssembly/binaryen/test/wasm-install/wasm-install/bin/../lib/clang/3.9.0/lib/linux/libclang_rt.ubsan_standalone-x86_64.a:

[dschuff]

Fixed by #52