Multiple Autotools improvements

Multiple Autotools improvements

- Defines some dependencies between shared libraries
- updates version.h only when version changes

Updating version.h on each "make" and "make install" was causing issues with
parallel builds. "make install" was re-linking vpp binary due to "updated"
version.h and in parallel it was re-linking shared libraries as part of
installation process. That was resulting on sporadic build failures.

Change-Id: I2a27ae1aea6a7a4100822018e095a60dd48d39ca
Signed-off-by: Damjan Marion <[email protected]>