fix raco ctool --c-mods' for racket'

Merge to 5.2.1

original commit: 6c4cd0e9c2

collects/tests/racket/ctool.rkt

@@ -0,0 +1,19 @@
+#lang racket
+(require setup/dirs)
+
+(define raco (build-path (find-console-bin-dir)
+                         (if (eq? (system-type) 'windows)
+                             "raco.exe"
+                             "raco")))
+
+(define tmp (make-temporary-file))
+
+(system* raco
+         "ctool"
+         "--3m"
+         "--c-mods"
+         tmp
+         "++lib"
+         "racket")
+
+(delete-file tmp)