is a vararg function.
The original code was examining flag OutputArg::IsFixed to determine whether
CC_MipsN_VarArg or CC_MipsN should be called. This is not correct, since this
flag is often set to false when the function being analyzed is a non-variadic
function.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174442 91177308-0d34-0410-b5e6-96231b3b80d8
