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, 2 deletions

diff --git a/tests/scripts/features/load b/tests/scripts/features/load
index 47267fe..78d5c51 100644
--- a/tests/scripts/features/load
+++ b/tests/scripts/features/load
@@ -21,14 +21,14 @@ print $F <<'EOF' ;
 #include "gnumake.h"
 
 int
-testload_gmk_setup ()
+testload_gmk_setup (gmk_floc *pos)
 {
     gmk_eval ("TESTLOAD = implicit", 0);
     return 1;
 }
 
 int
-explicit_setup ()
+explicit_setup (gmk_floc *pos)
 {
     gmk_eval ("TESTLOAD = explicit", 0);
     return 1;