iproute2: split iproute2 configure and compile logic

iproute2: split iproute2 configure and compile logic

Previously we relied on the iproute2 makefile automatically running the
configure script on first run. This does not allow control of some
configure options, or of when the configure script is re-run.

The motivating usecase here is ./configure --color=auto, though that is
not implemented in this commit.

Signed-off-by: George Tsiamasiotis <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/20281
Signed-off-by: Robert Marko <[email protected]>