move call/cc and call/ec to racket/private/more-scheme

Those aliases were moved out of `#%kernel` as part of the
determinstic-bytecode changes, but putting them in
`racket/private/pre-base` meant that they weren't included in
`mzscheme` or Pretty Big. The new location is with `let/cc`, which
makes more sense, and makes them picked up by `mzscheme` and Pretty
Big.

racket/collects/racket/private/more-scheme.rkt

@@ -298,6 +298,9 @@
 	    stx
 	    (let-values ([(temp ...) expr])
 	      (set! id temp) ...)))])))
+  
+  (define-values (call/cc) call-with-current-continuation)
+  (define-values (call/ec) call-with-escape-continuation)
 
   (define-syntax let/cc
     (lambda (stx)
@@ -386,6 +389,6 @@
              (rename break-paramz? break-parameterization?)
              with-handlers with-handlers* call-with-exception-handler
              set!-values
-             let/cc fluid-let time
+             let/cc call/cc call/ec fluid-let time
              log-fatal log-error log-warning log-info log-debug define-logger
              hash-ref! hash-has-key? hash-update hash-update!))

racket/collects/racket/private/pre-base.rkt

@@ -149,9 +149,6 @@
              stx)
             (raise-syntax-error #f "bad syntax" stx)))))
   
-  (define-values (call/cc) call-with-current-continuation)
-  (define-values (call/ec) call-with-escape-continuation)
-
   (#%provide (all-from-except "more-scheme.rkt" old-case fluid-let)
              (all-from-except "misc.rkt" collection-path collection-file-path)
              (all-from "define.rkt")
@@ -210,5 +207,4 @@
              define-struct/derived
              struct-field-index
              struct-copy
-             double-flonum?
-             call/cc call/ec))
+             double-flonum?))