Set LangOpts.ObjC1 to 1 in clang-format.

This matches the test change done in clang at r171742. Without this,
clang-format would strip '@' characters and format e.g. '@interface' as
'interface'.



git-svn-id: https://llvm.org/svn/llvm-project/clang-tools-extra/trunk@171743 91177308-0d34-0410-b5e6-96231b3b80d8