x86/vdso: Fix rethunk patching for vdso-image-x32.o too

In a similar fashion to

  b388e57d ("x86/vdso: Fix rethunk patching for vdso-image-{32,64}.o")

annotate vdso-image-x32.o too for objtool so that it gets annotated
properly and the unused return thunk warning doesn't fire.
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202403251454.23df6278-lkp@intel.comSigned-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/202403251454.23df6278-lkp@intel.com

arch/x86/entry/vdso/Makefile

@@ -41,6 +41,7 @@ obj-$(CONFIG_X86_X32_ABI)			+= vdso-image-x32.o
 obj-$(CONFIG_COMPAT_32)				+= vdso-image-32.o vdso32-setup.o
 
 OBJECT_FILES_NON_STANDARD_vdso-image-32.o	:= n
+OBJECT_FILES_NON_STANDARD_vdso-image-x32.o	:= n
 OBJECT_FILES_NON_STANDARD_vdso-image-64.o	:= n
 OBJECT_FILES_NON_STANDARD_vdso32-setup.o	:= n