CodeGen: fix section names for different file formats

This changes the codegen to match the section names according to the
ObjC rewriter as well as the runtime.  The changes to the test are
simply whitespace changes to the section attributes and names and are
functionally equivalent (the whitespace is ignored by the linker).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@304661 91177308-0d34-0410-b5e6-96231b3b80d8