Fix interfacing with and remaking dynamic objects on MS-Windows.

 load.c (load_object, load_file): Accept an additional argument
 DLP and return in it a pointer that can be used to unload the
 dynamic object.
 read.c (eval): Call load_file with an additional argument, and
 record the pointer returned there in the 'struct file' object of
 dynamic objects in that object's 'struct file'.
 commands.c (execute_file_commands): Unload dynamic objects
 before remaking them, to avoid failure to remake if the OS doesn't
 allow overwriting objects that are in use.
 filedef.h (struct file): New member dlopen_ptr.
 gnumake.h (GMK_EXPORT): Define to dllexport/dllimport
 decorations for Windows and to nothing on other platforms.
 (gmk_eval, gmk_expand, gmk_add_function): Add GMK_EXPORT qualifier
 to prototypes.
 makeint.h (MAIN): Define before including gnumake.h, to give
 correct dllexport decorations to exported functions.
 (load_file): Adjust prototype.
 loadapi.c: Don't include gnumake.h, since makeint.h already
 includes it, and takes care of defining MAIN before doing so.
 build_w32.bat (LinkGCC): Produce an import library for functions
 exported by Make for loadable dynamic objects.

 w32/compat/posixfcn.c (dlclose): New function.
 w32/include/dlfcn.h (dlclose): Add prototype.

 scripts/features/load: Fix signatures of testload_gmk_setup and
 explicit_setup, to bring them in line with the documentation.

1 files changed, 2 insertions, 0 deletions

diff --git a/filedef.h b/filedef.h
index b6ba242..50eec74 100644
--- a/filedef.h
+++ b/filedef.h
@@ -61,6 +61,8 @@ struct file
     int command_flags;		/* Flags OR'd in for cmds; see commands.h.  */
     char update_status;         /* Status of the last attempt to update,
 				   or -1 if none has been made.  */
+    void *dlopen_ptr;		/* For dynamic loaded objects: pointer to
+				   pass to dlclose to unload the object.  */
     enum cmd_state		/* State of the commands.  */
       {		/* Note: It is important that cs_not_started be zero.  */
 	cs_not_started,		/* Not yet started.  */