kbuild: fix segfault in modpost

Fix modpost segfault.

Before:
-------
ynezz@ntbk:~/linux-2.6.git$ scripts/mod/modpost vmlinux ath_pci.o
Segmentation fault

After:
------
ynezz@ntbk:~/linux-2.6.git$ scripts/mod/modpost vmlinux ath_pci.o
FATAL: section header offset=815726848 in file 'ath_pci.o' is bigger then filesize=153968

Sam: This seems to warn for a binutils issue. Anyway modpost should not
segfault.

Signed-off-by: Petr Stetiar <ynezz@true.cz>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>