setup/dirs: don't include (find-dll-dir) in (get-lib-search-dirs)

I don't see a reason to include `(find-dll-dir)` in the result of
`(get-lib-search-dirs)`. It's practically always redundant, and
including it causes problems for sandboxes --- since `(find-dll-dir)`
must inspect the Racket executable on Windows and Mac OS X, and that
access is normally not allowed by a sandbox.

pkgs/racket-pkgs/racket-doc/scribblings/raco/setup.scrbl

@@ -1161,6 +1161,26 @@ function for installing a single @filepath{.plt} file.
   Returns a path to a user-specific @filepath{lib} directory; the directory
   indicated by the returned path may or may not exist.}
 
+@defproc[(get-lib-search-dirs) (listof path?)]{
+  Returns a list of paths to search for foreign libraries. Unless it is
+  configured otherwise, the result includes any non-@racket[#f] result of
+  @racket[(find-lib-dir)] and
+  and @racket[(find-user-lib-dir)]---but the latter is included only if the
+  value of the @racket[use-user-specific-search-paths] parameter
+  is @racket[#t].
+
+  @history[#:changed "6.1.1.4" @elem{Dropped @racket[(find-dll-dir)]
+                                     from the set of paths to
+                                     explicitly include in the
+                                     default.}]}
+
+@defproc[(find-dll-dir) (or/c path? #f)]{
+  Returns a path to the directory that contains DLLs for use with the
+  current executable (e.g., @filepath{libracket.dll} on Windows).
+  The result is @racket[#f] if no such directory is available, or if no
+  specific directory is available (i.e., other than the platform's normal
+  search path).}
+
 @defproc[(find-share-dir) (or/c path? #f)]{ Returns a path to the
   installation's @filepath{share} directory, which contains installed
   packages and other platform-independent files. The result is
@@ -1170,21 +1190,6 @@ function for installing a single @filepath{.plt} file.
   Returns a path to a user-specific @filepath{share} directory; the directory
   indicated by the returned path may or may not exist.}
 
-@defproc[(find-dll-dir) (or/c path? #f)]{
-  Returns a path to the directory that contains DLLs for use with the
-  current executable (e.g., @filepath{libmzsch.dll} on Windows).
-  The result is @racket[#f] if no such directory is available, or if no
-  specific directory is available (i.e., other than the platform's normal
-  search path).}
-
-@defproc[(get-lib-search-dirs) (listof path?)]{
-  Returns a list of paths to search for foreign libraries. Unless it is
-  configured otherwise, the result includes any non-@racket[#f] result of
-  @racket[(find-lib-dir)], @racket[(find-dll-dir)],
-  and @racket[(find-user-lib-dir)]---but the last is included only if the
-  value of the @racket[use-user-specific-search-paths] parameter
-  is @racket[#t].}
-
 @defproc[(find-include-dir) (or/c path? #f)]{
   Returns a path to the installation's @filepath{include} directory, which
   contains @filepath{.h} files for building Racket extensions and embedding

racket/collects/setup/dirs.rkt

@@ -234,7 +234,7 @@
   find-lib-dir
   find-user-lib-dir
   config:lib-search-dirs
-  get-lib-search-dirs find-dll-dir
+  get-lib-search-dirs
   "lib")
 
 ;; ----------------------------------------