build/trivial: prettify makefiles by wrapping long lines

Signed-off-by: Thomas Haller <thaller@redhat.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
build: move copy of linux headers to private directory

libnl3 contains a private copy of some kernel header files.

Normally, users are expected to install libnl and specify
-I$PREFIX/include/libnl3 as include path. As the private kernel
header files are not installed, this works fine.

However, it can be convenient to build against the libnl source
directory, without installing libnl. In this case, the private kernel
header files shaddow the system provided ones. This is undesired.

Move these files to a different directory to avoid this clash.

http://lists.infradead.org/pipermail/libnl/2014-September/001645.html

Signed-off-by: Thomas Haller <thaller@redhat.com>
Acked-by: Thomas Graf <tgraf@suug.ch>