Move -Wreorder to cxxflag (instead of common, which impacts cflags) (#1881)
Move -Wreorder to cxxflag (instead of common, which impacts cflags) (#1881)

-Wreorder is not a valid cflag on at least linux/gcc.
firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk,firebase/firebase-ios-sdk