This diff includes changes for supporting the following types.

This diff includes changes for supporting the following types.

```

// Primary fixed point types
signed short _Accum s_short_accum;
signed _Accum s_accum;
signed long _Accum s_long_accum;
unsigned short _Accum u_short_accum;
unsigned _Accum u_accum;
unsigned long _Accum u_long_accum;

// Aliased fixed point types
short _Accum short_accum;
_Accum accum;
long _Accum long_accum;

```

This diff only allows for declaration of the fixed point types. Assignment and other operations done on fixed point types according to http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1169.pdf will be added in future patches. The saturated versions of these types and the equivalent `_Fract` types will also be added in future patches.

The tests included are for asserting that we can declare these types.

Differential Revision: https://reviews.llvm.org/D46084

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@333814 91177308-0d34-0410-b5e6-96231b3b80d8