Don't compute a patched/semantic storage class.

For variables and functions clang used to store two storage classes. The one
"as written" in the code and a patched one, which, for example, propagates
static to the following decls.

This apparently is from the days clang lacked linkage computation. It is now
redundant and this patch removes it.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@178663 91177308-0d34-0410-b5e6-96231b3b80d8