bug#54990: Byte compiler bug

[Mattias Engdegård]

This is related to symbol positioning so Alan should be well-placed to debug 
it. (The symbol names are irrelevant.)

It's `compile-defun` that is broken; the constant vector of the resulting 
bytecode contains symbols with position as hash table keys for a switch 
operation. Compare the bytecode object with that from `byte-compile` which 
works correctly:

(defun tata (x)
  (cond
   ((eq x 'a) 'toto)
   ((eq x 'b) 'titi)))

(byte-compile 'tata)
=>
#[257 "..." [#s(hash-table size 2 test eq rehash-size 1.5 rehash-threshold 
0.8125 purecopy t data (a 6 b 8)) toto titi nil] 3 "..."]

;; if using `compile-defun` on `tata`:
(symbol-function 'tata)
#[257 "..." [#s(hash-table size 2 test eq rehash-size 1.5 rehash-threshold 
0.8125 purecopy t data (#<symbol a at 293> 6 #<symbol b at 314> 8)) toto titi 
nil] 3 "..."]