dsound: Make id_to_offset() static.

dlls/dinput/device.c

diff --git a/dlls/dinput/device.c b/dlls/dinput/device.c
index cf91153..c0f15ff 100644
--- a/dlls/dinput/device.c
+++ b/dlls/dinput/device.c
@@ -510,7 +510,7 @@
     return -1;
 }
 
-int id_to_offset(const DataFormat *df, int id)
+static int id_to_offset(const DataFormat *df, int id)
 {
     int obj = id_to_object(df->wine_df, id);
 

dlls/dinput/device_private.h

diff --git a/dlls/dinput/device_private.h b/dlls/dinput/device_private.h
index d62e32e..43b28c9 100644
--- a/dlls/dinput/device_private.h
+++ b/dlls/dinput/device_private.h
@@ -81,7 +81,6 @@
 extern void queue_event(LPDIRECTINPUTDEVICE8A iface, int inst_id, DWORD data, DWORD time, DWORD seq);
 /* Helper functions to work with data format */
 extern int id_to_object(LPCDIDATAFORMAT df, int id);
-extern int id_to_offset(const DataFormat *df, int id);
 extern int find_property(const DataFormat *df, LPCDIPROPHEADER ph);
 
 /* Common joystick stuff */