message: Fix configuration of the use of concepts
diff: @@ -286,7 +286,7 @@ install:
  - mkdir -p build
  # This cd works, but causes the shell to exit on OSX with set -e. I don't even.
  - set +e; cd build; set -e; pwd
  - - cmake .. -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DCMAKE_CXX_FLAGS="${CXX_FLAGS}" -DCMAKE_EXE_LINKER_FLAGS="${CXX_LINKER_FLAGS}" -DRANGES_CXX_STD=$CPP -DRANGE_V3_HEADER_CHECKS=$HEADERS -DRANGE_V3_PREFER_REAL_CONCEPTS=$CONCEPTS -DRANGES_VERBOSE_BUILD=On -DRANGES_ASAN=$ASAN -DRANGES_MSAN=$MSAN -DRANGES_DEEP_STL_INTEGRATION=On -Wdev
  + - cmake .. -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DCMAKE_CXX_FLAGS="${CXX_FLAGS}" -DCMAKE_EXE_LINKER_FLAGS="${CXX_LINKER_FLAGS}" -DRANGES_CXX_STD=$CPP -DRANGE_V3_HEADER_CHECKS=$HEADERS -DRANGES_PREFER_REAL_CONCEPTS=$CONCEPTS -DRANGES_VERBOSE_BUILD=On -DRANGES_ASAN=$ASAN -DRANGES_MSAN=$MSAN -DRANGES_DEEP_STL_INTEGRATION=On -Wdev
  - cat CMakeFiles/CMakeError.log || true
  - cat CMakeFiles/CMakeOutput.log || true
  - if [ "$CLANG_MODULES" == "On" -a "$LIBCXX" == "On" ]; then cmake .. -DRANGES_MODULES=On -DRANGES_LIBCXX_MODULE="${TRAVIS_BUILD_DIR}/llvm/include/c++/v1/module.modulemap"; fi
  