Generic hashtable causes SEGV

[Takashi Kato]

When the compare (even and hasher) procedure accepts variable arguments then hashtable may cause SEGV

(import (rnrs))
(define ht (make-hashtable eqv-hash =))
(hashtable-set! ht 0 1)
(hashtable-set! ht 0 1)

This is because hashtable comparison is immatually optimised.

[Takashi Kato]

Adding optional argument check for generic hashtable. (Fixes #84)

→ <<cset b61a45e247f3>>