A *.mod file lists the member objects of a module, but vmlinux does
not have such a file.

Generate this list to allow modpost to know all the member objects.
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
Reviewed-by: NNicolas Schier <nicolas@fjasle.eu>
Tested-by: NNathan Chancellor <nathan@kernel.org>