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, 7 insertions, 2 deletions

diff --git a/makeint.h b/makeint.h
index 812ead1..535db1d 100644
--- a/makeint.h
+++ b/makeint.h
@@ -48,8 +48,12 @@ char *alloca ();
 #endif
 
 /* Include the externally-visible content.
-   Be sure to use the local one, and not one installed on the system.  */
+   Be sure to use the local one, and not one installed on the system.
+   Define MAIN for proper selection of dllexport/dllimport declarations
+   for MS-Windows.  */
+#define MAIN
 #include "gnumake.h"
+#undef MAIN
 
 #ifdef  CRAY
 /* This must happen before #include <signal.h> so
@@ -476,7 +480,8 @@ int guile_gmake_setup (const gmk_floc *flocp);
 
 /* Loadable object support.  Sets to the strcached name of the loaded file.  */
 typedef int (*load_func_t)(const gmk_floc *flocp);
-int load_file (const gmk_floc *flocp, const char **filename, int noerror);
+int load_file (const gmk_floc *flocp, const char **filename, int noerror,
+	       void **dlp);
 
 #ifdef  HAVE_VFORK_H
 # include <vfork.h>