Ignore some warnings on clang.

.travis.yml

@@ -12,6 +12,7 @@ before_install:
     - sudo add-apt-repository -y ppa:saiarcot895/chromium-beta
     - sudo apt-get --yes update
     - sudo apt-get --yes install g++-4.8
+    - if [ "$CXX" == "g++" ]; then export CXX=g++-4.8; fi
     - sudo apt-get --yes install ninja-build
     - sudo apt-get --yes install liblua5.2-dev
 

bootstrap.py

@@ -66,6 +66,9 @@ if args.debug:
 else:
     cxxflags.extend(['-DNDEBUG', '-O3'])
 
+if args.cxx == 'clang++':
+    cxxflags.extend(['-Wno-unused-value', '-Wno-constexpr-not-const'])
+
 if args.lua_dir:
     include.extend([os.path.join(args.lua_dir, 'include')])
     ldflags.extend(library_includes([os.path.join(args.lua_dir, 'lib')]))