wanted: more compiler smartness regarding constant strings operations

[Roman Marynchak]

This code compiles without any claims:

(defun s() (write-string "My string" nil :start 1 :end 344))

Obviously, it fails to execute:

debugger invoked on a SB-KERNEL:BOUNDING-INDICES-BAD-ERROR in thread #<THREAD
                                                                       "initial thread" RUNNING
                                                                       {A9EB801}>:
  The bounding indices 1 and 344 are bad for a sequence of length 9.

This should be said at compile time. I guess that such problems are present not only in WRITE-STRING case.

Regards,
Roman