CTFE: Don't declare tuples wrappers as variables

Only the members of the tuples are variables. The tuple itself
doesn't need storage.
CTFE: Don't declare local enums as variables

They don't go on the stack (they already get a slot in the
global constants table when they get used)
Merge pull request #1807 from donc/ctfeEnumsAintVars

CTFE: Enums and tuple wrappers are not variables