dinput: Constify some variables

[Andrew Talbot]

Changelog:
    dinput: Constify some variables.

diff -urN a/dlls/dinput/joystick_linux.c b/dlls/dinput/joystick_linux.c
--- a/dlls/dinput/joystick_linux.c	2007-02-06 22:18:59.000000000 +0000
+++ b/dlls/dinput/joystick_linux.c	2007-02-12 20:28:05.000000000 +0000
@@ -113,7 +113,7 @@
 	POV				povs[4];
 };
 
-static GUID DInput_Wine_Joystick_GUID = { /* 9e573ed9-7734-11d2-8d4a-23903fb6bdf7 */
+static const GUID DInput_Wine_Joystick_GUID = { /* 9e573ed9-7734-11d2-8d4a-23903fb6bdf7 */
   0x9e573ed9,
   0x7734,
   0x11d2,
diff -urN a/dlls/dinput/keyboard.c b/dlls/dinput/keyboard.c
--- a/dlls/dinput/keyboard.c	2007-01-11 15:27:49.000000000 +0000
+++ b/dlls/dinput/keyboard.c	2007-02-12 20:28:14.000000000 +0000
@@ -93,7 +93,7 @@
     return CallNextHookEx(0, code, wparam, lparam);
 }
 
-static GUID DInput_Wine_Keyboard_GUID = { /* 0ab8648a-7735-11d2-8c73-71df54a96441 */
+static const GUID DInput_Wine_Keyboard_GUID = { /* 0ab8648a-7735-11d2-8c73-71df54a96441 */
   0x0ab8648a,
   0x7735,
   0x11d2,
diff -urN a/dlls/dinput/mouse.c b/dlls/dinput/mouse.c
--- a/dlls/dinput/mouse.c	2007-01-11 15:27:49.000000000 +0000
+++ b/dlls/dinput/mouse.c	2007-02-12 20:28:30.000000000 +0000
@@ -73,7 +73,7 @@
 /* FIXME: This is ugly and not thread safe :/ */
 static IDirectInputDevice8A* current_lock = NULL;
 
-static GUID DInput_Wine_Mouse_GUID = { /* 9e573ed8-7734-11d2-8d4a-23903fb6bdf7 */
+static const GUID DInput_Wine_Mouse_GUID = { /* 9e573ed8-7734-11d2-8d4a-23903fb6bdf7 */
     0x9e573ed8,
     0x7734,
     0x11d2,