std: update std.builtin.Type fields to follow naming conventions

The compiler actually doesn't need any functional changes for this: Sema
does reification based on the tag indices of `std.builtin.Type` already!
So, no zig1.wasm update is necessary.

This change is necessary to disallow name clashes between fields and
decls on a type, which is a prerequisite of #9938.

tools/generate_c_size_and_align_checks.zig

@@ -43,7 +43,7 @@ pub fn main() !void {
     const target = try std.zig.system.resolveTargetQuery(query);
 
     const stdout = std.io.getStdOut().writer();
-    inline for (@typeInfo(std.Target.CType).Enum.fields) |field| {
+    inline for (@typeInfo(std.Target.CType).@"enum".fields) |field| {
         const c_type: std.Target.CType = @enumFromInt(field.value);
         try stdout.print("_Static_assert(sizeof({0s}) == {1d}, \"sizeof({0s}) == {1d}\");\n", .{
             cName(c_type),