Evaluate dumper-action-forms in CL-USER package.

Currently the dumper-action-forms are evaluated in the (gensym "DUMPER") package. This creates the possibility for missing package errors when load is executed in another image. Here's a minimal example that triggers the undesirable behavior which this patch fixes:

    buildapp \
        --eval "(load (compile-file \"/home/matt/libs/buildapp/test.lisp\"))" \
        --output ~/bin/irrelevant 

    ;;;; test.lisp

    (print 'foo)

    ;;;;  load the fasl buildapp created from test.lisp into any image.
    * (load "test")

    debugger invoked on a SB-KERNEL:SIMPLE-PACKAGE-ERROR in thread
    #<THREAD "main thread" RUNNING {1002AC3153}>:
      The name "DUMPER697" does not designate any package.