Installing headers and static libraries to the target system seems
to be not required for most use cases, so let's factor them
out into a dedicated -dev package.
This cuts down to disk usage to around 50% of the original
package to ~ 2MB - not that disk space is an issue normally,
but when using inside an initramfs only project, it counts.
Signed-off-by: Michael Heimpold <mhei@heimpold.de>