scan/sane/orblite: Include <dflcn.h> for function prototypes

This is required for C99 compatibility.  Also delete the unused
bb_unload function because it calls a call to the undefined
_DBG function/macro.

Submitted upstream: <https://bugs.launchpad.net/hplip/+bug/1997875>

diff --git a/scan/sane/orblite.c b/scan/sane/orblite.c
index ba86640c7528fc9c..ac59dda9c2dba593 100644
--- a/scan/sane/orblite.c
+++ b/scan/sane/orblite.c
@@ -20,6 +20,7 @@
 #include "orblitei.h"
 #include "orblite.h"//Added New
 #include <math.h>
+#include <dlfcn.h>
 #include "utils.h"
 #include "io.h"
 
@@ -193,27 +194,6 @@ bugout:
 
 }
 
-static int bb_unload(SANE_THandle ps)
-{
-   _DBG("Calling orblite bb_unload: \n");
-   if (ps->bb_handle)
-   {
-      dlclose(ps->bb_handle);
-      ps->bb_handle = NULL;
-   }
-   if (ps->hpmud_handle)
-   {
-      dlclose(ps->hpmud_handle);
-      ps->hpmud_handle = NULL;
-   }
-//   if (ps->math_handle)
-//   { 
-//      dlclose(ps->math_handle);
-//      ps->math_handle = NULL;
-//   }
-   return 0;
-}
-
 SANE_Status 
 orblite_init (SANE_Int * version_code, SANE_Auth_Callback authorize)
 {