Keep track of the actual storage specifier written on a variable or

Keep track of the actual storage specifier written on a variable or
function declaration, since it may end up being changed (e.g.,
"extern" can become "static" if a prior declaration was static). Patch
by Enea Zaffanella and Paolo Bolzoni.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@101826 91177308-0d34-0410-b5e6-96231b3b80d8