patch applied (ghc): Update the panic msg from #1257 to be an ordinary error, not a panic

[Simon Marlow]

Fri May 18 05:12:29 PDT 2007  Simon Marlow <simonmar at microsoft.com>
  * Update the panic msg from #1257 to be an ordinary error, not a panic
  We don't support arbitrary unboxed tuples in GHCi right now.

    M ./compiler/ghci/ByteCodeGen.lhs -4 +5