[PATCH] vbox: fix link error with 'gcc -Og'

[Arnd Bergmann]

With the new CONFIG_CC_OPTIMIZE_FOR_DEBUGGING option, we get a link
error in the vboxguest driver, when that fails to optimize out the
call to the compat handler:

drivers/virt/vboxguest/vboxguest_core.o: In function `vbg_ioctl_hgcm_call':
vboxguest_core.c:(.text+0x1f6e): undefined reference to `vbg_hgcm_call32'

Another compile-time check documents better what we want and avoids
the error.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>

diff --git a/drivers/virt/vboxguest/vboxguest_core.c
b/drivers/virt/vboxguest/vboxguest_core.c
index 3093655c7b92..1475ed5ffcde 100644
--- a/drivers/virt/vboxguest/vboxguest_core.c
+++ b/drivers/virt/vboxguest/vboxguest_core.c
@@ -1312,7 +1312,7 @@ static int vbg_ioctl_hgcm_call(struct vbg_dev *gdev,
 		return -EINVAL;
 	}

-	if (f32bit)
+	if (IS_ENABLED(CONFIG_COMPAT) && f32bit)
 		ret = vbg_hgcm_call32(gdev, client_id,
 				      call->function, call->timeout_ms,
 				      VBG_IOCTL_HGCM_CALL_PARMS32(call),