repair no-executables assemble-distribution on Windows

Repairs a problem with `raco c-tool --c-mods <file> --runtime <dir>`
as reported by Dmitry Pavlov.

pkgs/compiler-test/tests/compiler/ctool.rkt

@@ -7,6 +7,7 @@
                              "raco")))
 
 (define tmp (make-temporary-file))
+(define tmp-dir (make-temporary-file "mztmp~a" 'directory))
 
 (system* raco
          "ctool"
@@ -16,4 +17,15 @@
          "++lib"
          "racket")
 
+(system* raco
+         "ctool"
+         "--3m"
+         "--c-mods"
+         tmp
+         "++lib"
+         "racket/promise"
+         "--runtime"
+         tmp-dir)
+
 (delete-file tmp)
+(delete-directory/files tmp-dir)

racket/collects/compiler/distribute.rkt

@@ -110,6 +110,7 @@
         (install-libs lib-dir types
 		      #:extras-only? (not executables?)
 		      #:no-dlls? (and (eq? 'windows (cross-system-type))
+				      executables?
 				      ;; If all executables have "<system>" the the
 				      ;; DLL dir, then no base DLLS are needed
 				      (for/and ([f (in-list orig-binaries)])