Document that -fsanitize=function is Linux-only.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@193452 91177308-0d34-0410-b5e6-96231b3b80d8
ObjectiveC arc. Warn when an implicitly 'strong' property 
is redeclared as 'weak' in class extension.
// rdar://15304886


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@193453 91177308-0d34-0410-b5e6-96231b3b80d8