message: cmake: don't require stdlib=libc++ for clang
  With this flag, the clang build lead to many linking errors on a Linux
  such as Fedora.
diff: @@ -36,7 +36,8 @@ endif()
  # Clang needs this warning disabled.
  if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
  - add_definitions("-stdlib=libc++ -Wno-missing-braces")
  + # Some time ago we needed `-stdlib=libc++` but that does not seem to be true anymore.
  + add_definitions("-Wno-missing-braces")
  endif()
  if (ANDROID)
  