builddeb: use $OBJCOPY variable instead of objcopy
builddeb: use $OBJCOPY variable instead of objcopy

In cross-build environment, we expect to use the cross-compiler objcopy
instead of the host objcopy.

It fixes following build failures:
objcopy --only-keep-debug lib/modules/3.14/kernel/net/ipv6/xfrm6_mode_tunnel.ko /srv/build/linux/debian/dbgtmp/usr/lib/debug/lib/modules/3.14/kernel/net/ipv6/xfrm6_mode_tunnel.ko
objcopy: Unable to recognise the format of the input file `lib/modules/3.14/kernel/net/ipv6/xfrm6_mode_tunnel.ko'

Signed-off-by: Fathi Boudra <7cd6e55cc07a66bc71d7901a4cddfe6c22aab659@linaro.org>
Cc: stable <4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@vger.kernel.org> # 3.12+
Fixes: 810e843746b7 ('deb-pkg: split debug symbols in their own package')
Reviewed-by: Ben Hutchings <73675debcd8a436be48ec22211dcf44fe0df0a64@decadent.org.uk>
Signed-off-by: Michal Marek <0c835876a532a476f30fdb1f6e963bae6c5a1a04@suse.cz>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs