Revert r166370 and r166540 now that Xcode 4.6 has been available for a while.

Those changes were added as a temporary workaround for Xcode 4.5 passing the
-Wno-arc-abi option.  Xcode 4.6 does not pass that option so this should no
longer be necessary.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@176887 91177308-0d34-0410-b5e6-96231b3b80d8
Move the extern "C" sema tests to a new file.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@176888 91177308-0d34-0410-b5e6-96231b3b80d8
Objective-C: Issue warning in couple of obscure cases
when property autosynthesis does not synthesize a property.
When property is declared 'readonly' in a super class and
is redeclared 'readwrite' in a subclass. When a property
autosynthesis causes it to share 'ivar' with another property.
// rdar://13388503


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@176889 91177308-0d34-0410-b5e6-96231b3b80d8
Add an interesting testcase we already handle correctly.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@176890 91177308-0d34-0410-b5e6-96231b3b80d8
Make C++11 status page more consistent: we mark entries as "done" if we
implement correct functionality, even if it's not optimal. On this basis, mark
"data dependency ordering" as done. Add footnotes for cases where our
implementation is known to be suboptimal.


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@176891 91177308-0d34-0410-b5e6-96231b3b80d8