Fix some mzlib references.

racket/src/mac/osx_appl.rkt

@@ -11,8 +11,9 @@
 (module osx_appl mzscheme
 
   (require (lib "plist.rkt" "xml")
-	   mzlib/process
-	   mzlib/file)
+	   racket/system
+	   racket/file
+           racket/path)
 
   (define rez-path (or (getenv "REZ")
 		       "/Developer/Tools/Rez"))

racket/src/racket/gc/upgrade.rkt

@@ -3,8 +3,7 @@
 (define new-dir "~/Desktop/gc6.7")
 (define really-git? #t)
 
-(require mzlib/file
-	 mzlib/process)
+(require racket/file racket/path racket/system)
 
 (define old (make-hash-table 'equal))
 (define new (make-hash-table 'equal))

racket/src/worksp/gc2/make.rkt

@@ -3,7 +3,7 @@
 (use-compiled-file-paths null)
 
 (require mzlib/restart
-         mzlib/process)
+         racket/system)
 
 (define (system- s)
   (eprintf "~a\n" s)