Escape more @ signs in Doxygen comments.

Doxygen treats "@command" the same as "\command" in a doc comment, so
whenever we talk about Objective-C things like "@interface" we have to
make sure to escape them.

Let's try to keep Clang -Wdocumentation-clean!

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178603 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed