virtio-gpu: only compile virtio-gpu-3d.c for CONFIG_VIRGL=y

There is no actual code in the CONFIG_VIRGL=n case.  So building is
(a) pointless and (b) makes macos ranlib complain.

Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-id: 20201026142851.28735-1-kraxel@redhat.com

hw/display/meson.build

@@ -57,7 +57,9 @@ softmmu_ss.add(when: [pixman, 'CONFIG_ATI_VGA'], if_true: files('ati.c', 'ati_2d
 if config_all_devices.has_key('CONFIG_VIRTIO_GPU')
   virtio_gpu_ss = ss.source_set()
   virtio_gpu_ss.add(when: 'CONFIG_VIRTIO_GPU',
-                    if_true: [files('virtio-gpu-base.c', 'virtio-gpu.c', 'virtio-gpu-3d.c'), pixman, virgl])
+                    if_true: [files('virtio-gpu-base.c', 'virtio-gpu.c'), pixman, virgl])
+  virtio_gpu_ss.add(when: ['CONFIG_VIRTIO_GPU', 'CONFIG_VIRGL'],
+                    if_true: [files('virtio-gpu-3d.c'), pixman, virgl])
   virtio_gpu_ss.add(when: 'CONFIG_VHOST_USER_GPU', if_true: files('vhost-user-gpu.c'))
   hw_display_modules += {'virtio-gpu': virtio_gpu_ss}
 endif

hw/display/virtio-gpu-3d.c

@@ -17,8 +17,6 @@
 #include "hw/virtio/virtio.h"
 #include "hw/virtio/virtio-gpu.h"
 
-#ifdef CONFIG_VIRGL
-
 #include <virglrenderer.h>
 
 static struct virgl_renderer_callbacks virtio_gpu_3d_cbs;
@@ -633,5 +631,3 @@ int virtio_gpu_virgl_get_num_capsets(VirtIOGPU *g)
 
     return capset2_max_ver ? 2 : 1;
 }
-
-#endif /* CONFIG_VIRGL */