util-linux: use configure option instead of patching makefile

Use --disable-all-programs configure option instead of sed base
patching of Makefile.am in case no util-linux binaries are selected.

Suggested by Thomas Petazzoni ([1]).

With this patch applied the following libs are no longer build by default:

util-linux-2.25.1/.libs/libfdisk.a
util-linux-2.25.1/.libs/libsmartcols.a
util-linux-2.25.1/.libs/libsmartcols.so.1.1.0

[1] http://lists.busybox.net/pipermail/buildroot/2014-October/109818.html



Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>