It has been a request that multiple libnl versions should be installabe
in parallel.
In order to achieve this, the basename of the library was changed to
libnl-3 which reflects the 3rd generation of libnl APIs. It also means
that release based library versioning is left behind and libtool
versioning is used instead.
Projects using pkgconfig will automatically link against the new library
basename and will not notice a difference.
The SO versioning is based on the glib model:
current := 100 * minor + micro - revision
revision := revision
age := age (number of backwards compatible versions)
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