[1/11][Clang][Type] Expand BuiltinTypeBits from 8 to 9 bits

[eopXD]

Summary

This patch-set aims to expand all variants of the RVV segment
load/store intrinsics. The first commit expands the limitation of
builtin types from 256 to 512. The following patches expands the
full variants one-by-one.

The next patch introduces a number of new RVV tuple types and lets the
total of builtin types exceed the current limit (256). This patch
attempts to increase the bits used so we can continue to expand new
builtin types.

[erichkeane]

clang/include/clang/AST/Type.h

1652

It looks like the largest of the Bitfields in the union uses 32 bits (an unsigned), so this doesn't grow anything as far as I can tell, right?

Based on your requirements, I'd rather we do 1 of 2 things;

1- Make this 9 bits (or 10, or whatever is NECESSARY).
2- Just make this an unsigned, which doesn't grow the size, and put a comment on it that we can steal bits from it if needed.

[eopXD]

Address comment from Erich.

[eopXD]

Rebase upon landing of D152429.

clang/include/clang/AST/Type.h

protected:
   };
 
   class BuiltinTypeBitfields {
     friend class BuiltinType;
 
     unsigned : NumTypeBits;
 
     /// The kind (BuiltinType::Kind) of builtin type this is.
-    unsigned Kind : 8;
+    unsigned Kind : 16;
   };
 
   /// FunctionTypeBitfields store various bits belonging to FunctionProtoType.
   /// Only common bits are stored here. Additional uncommon bits are stored
   /// in a trailing object after FunctionProtoType.
   class FunctionTypeBitfields {
     friend class FunctionProtoType;
     friend class FunctionType;