nvidia-settings: Make VDPAUDeviceFunctions static to ctkvdpau.c

GCC 10 defaults to building with -fno-common, which exposes a bug in
nvidia-settings: The VDPAUDeviceFunctions structure is defined as global in
ctkvdpau.h, so both ctkvdpau.o and ctkwindow.o have it as a global, non-static
"tentative definition" symbol. The GCC 10 man page describes it like this:

       -fcommon
           In C code, this option controls the placement of global variables
           defined without an initializer, known as tentative definitions in
           the C standard.  Tentative definitions are distinct from
           declarations of a variable with the "extern" keyword, which do not
           allocate storage.

           The default is -fno-common, which specifies that the compiler
           places uninitialized global variables in the BSS section of the
           object file.  This inhibits the merging of tentative definitions by
           the linker so you get a multiple-definition error if the same
           variable is accidentally defined in more than one compilation unit.

           The -fcommon places uninitialized global variables in a common
           block.  This allows the linker to resolve all tentative definitions
           of the same variable in different compilation units to the same
           object, or to a non-tentative definition.  This behavior is
           inconsistent with C++, and on many targets implies a speed and code
           size penalty on global variable references.  It is mainly useful to
           enable legacy code to link without errors.

Since the copy of VDPAUDeviceFunctions in ctkwindow.o is not used, just remove
it by moving the definition of this structure into ctkvdpau.c.

src/gtk+-2.x/ctkvdpau.c

@@ -103,6 +103,29 @@ const gchar* __video_mixer_parameter_help =
 const gchar* __video_mixer_attribute_help =
 "This shows the video mixer attributes and any applicable ranges.";
 
+static struct VDPAUDeviceImpl {
+
+    VdpGetErrorString *GetErrorString;
+    VdpGetProcAddress *GetProcAddress;
+    VdpGetApiVersion *GetApiVersion;
+    VdpGetInformationString *GetInformationString;
+    VdpVideoSurfaceQueryCapabilities *VideoSurfaceQueryCapabilities;
+    VdpVideoSurfaceQueryGetPutBitsYCbCrCapabilities
+        *VideoSurfaceQueryGetPutBitsYCbCrCapabilities;
+    VdpOutputSurfaceQueryCapabilities *OutputSurfaceQueryCapabilities;
+    VdpOutputSurfaceQueryGetPutBitsNativeCapabilities
+        *OutputSurfaceQueryGetPutBitsNativeCapabilities;
+    VdpOutputSurfaceQueryPutBitsYCbCrCapabilities
+        *OutputSurfaceQueryPutBitsYCbCrCapabilities;
+    VdpBitmapSurfaceQueryCapabilities *BitmapSurfaceQueryCapabilities;
+    VdpDecoderQueryCapabilities *DecoderQueryCapabilities;
+    VdpVideoMixerQueryFeatureSupport *VideoMixerQueryFeatureSupport;
+    VdpVideoMixerQueryParameterSupport *VideoMixerQueryParameterSupport;
+    VdpVideoMixerQueryAttributeSupport *VideoMixerQueryAttributeSupport;
+    VdpVideoMixerQueryParameterValueRange *VideoMixerQueryParameterValueRange;
+    VdpVideoMixerQueryAttributeValueRange *VideoMixerQueryAttributeValueRange;
+} VDPAUDeviceFunctions;
+
 static int queryOutputSurface(CtkVDPAU *ctk_vdpau, VdpDevice device,
                               VdpGetProcAddress *getProcAddress);
 

src/gtk+-2.x/ctkvdpau.h

@@ -45,30 +45,6 @@ G_BEGIN_DECLS
 #define CTK_VDPAU_GET_CLASS(obj) \
     (G_TYPE_INSTANCE_GET_CLASS ((obj), CTK_TYPE_VDPAU, CtkVDPAUClass))
 
-
-struct VDPAUDeviceImpl {
-
-    VdpGetErrorString *GetErrorString;
-    VdpGetProcAddress *GetProcAddress;
-    VdpGetApiVersion *GetApiVersion;
-    VdpGetInformationString *GetInformationString;
-    VdpVideoSurfaceQueryCapabilities *VideoSurfaceQueryCapabilities;
-    VdpVideoSurfaceQueryGetPutBitsYCbCrCapabilities
-        *VideoSurfaceQueryGetPutBitsYCbCrCapabilities;
-    VdpOutputSurfaceQueryCapabilities *OutputSurfaceQueryCapabilities;
-    VdpOutputSurfaceQueryGetPutBitsNativeCapabilities
-        *OutputSurfaceQueryGetPutBitsNativeCapabilities;
-    VdpOutputSurfaceQueryPutBitsYCbCrCapabilities
-        *OutputSurfaceQueryPutBitsYCbCrCapabilities;
-    VdpBitmapSurfaceQueryCapabilities *BitmapSurfaceQueryCapabilities;
-    VdpDecoderQueryCapabilities *DecoderQueryCapabilities;
-    VdpVideoMixerQueryFeatureSupport *VideoMixerQueryFeatureSupport;
-    VdpVideoMixerQueryParameterSupport *VideoMixerQueryParameterSupport;
-    VdpVideoMixerQueryAttributeSupport *VideoMixerQueryAttributeSupport;
-    VdpVideoMixerQueryParameterValueRange *VideoMixerQueryParameterValueRange;
-    VdpVideoMixerQueryAttributeValueRange *VideoMixerQueryAttributeValueRange;
-} VDPAUDeviceFunctions;
-
 /* Generic description structure */
 typedef struct
 {