dln.c: fix EXTERNAL_PREFIX

* configure.in (EXPORT_PREFIX): revert r50410.

* dln.c (EXTERNAL_PREFIX): define by predefined macros.
  configured EXPORT_PREFIX is different thing.

* win32/Makefile.sub: r50414-50415.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50416 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

configure.in

@@ -3983,7 +3983,6 @@ AC_SUBST(SYMBOL_PREFIX)
 AC_SUBST(MINIOBJS)
 AC_SUBST(THREAD_MODEL)
 AC_SUBST(PLATFORM_DIR)
-AC_DEFINE_UNQUOTED(EXPORT_PREFIX, "$EXPORT_PREFIX")
 
 firstmf=`echo $FIRSTMAKEFILE | sed 's/:.*//'`
 firsttmpl=`echo $FIRSTMAKEFILE | sed 's/.*://'`

dln.c

@@ -106,7 +106,12 @@ dln_loaderror(const char *format, ...)
 # define USE_DLN_DLOPEN
 #endif
 
-#define FUNCNAME_PREFIX EXPORT_PREFIX"Init_"
+#if defined(__hp9000s300) || ((defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)) && !defined(__ELF__)) || defined(__BORLANDC__) || defined(NeXT) || defined(__WATCOMC__) || defined(MACOSX_DYLD)
+# define EXTERNAL_PREFIX "_"
+#else
+# define EXTERNAL_PREFIX ""
+#endif
+#define FUNCNAME_PREFIX EXTERNAL_PREFIX"Init_"
 
 #if defined __CYGWIN__ || defined DOSISH
 #define isdirsep(x) ((x) == '/' || (x) == '\\')
@@ -1327,7 +1332,7 @@ dln_load(const char *file)
 # if defined RUBY_EXPORT
 	{
 	    static const char incompatible[] = "incompatible library version";
-	    void *ex = dlsym(handle, EXPORT_PREFIX"ruby_xmalloc");
+	    void *ex = dlsym(handle, EXTERNAL_PREFIX"ruby_xmalloc");
 	    if (ex && ex != ruby_xmalloc) {
 
 #   if defined __APPLE__

win32/Makefile.sub

@@ -749,7 +749,6 @@ $(CONFIG_H): $(MKFILES) $(srcdir)/win32/Makefile.sub $(win_srcdir)/Makefile.sub
 !if "$(EXTSTATIC)" == "static"
 #define EXTSTATIC 1
 !endif
-#define EXPORT_PREFIX "_"
 #define EXECUTABLE_EXTS $(EXECUTABLE_EXTS)
 #define RUBY_COREDLL "$(RT)"
 #define LIBRUBY_SO "$(LIBRUBY_SO)"