SEGV by invalid rename clause

[Takashi Kato]

This should raise an error during compilation but causes SEGV at runtime.

(library (foo)
    (export (rename (barfoo)))
    (import (rnrs))
  (define bar 'foo))

(import (foo))

[Takashi Kato]

Added check for R6RS style rename clause (Fixes #58)

→ <<cset 0a3bbe53aa96>>