mk: provide option to set major ABI version

mk: provide option to set major ABI version

Downstreams might want to provide different DPDK releases at the same
time to support multiple consumers of DPDK linked against older and newer
sonames.

Also due to the interdependencies that DPDK libraries can have applications
might end up with an executable space in which multiple versions of a
library are mapped by ld.so.

Think of LibA that got an ABI bump and LibB that did not get an ABI bump
but is depending on LibA.

    Application
    \-> LibA.old
    \-> LibB.new -> LibA.new

That is a conflict which can be avoided by setting CONFIG_RTE_MAJOR_ABI.
If set CONFIG_RTE_MAJOR_ABI overwrites any LIBABIVER value.
An example might be ``CONFIG_RTE_MAJOR_ABI=16.11`` which will make all
libraries librte<?>.so.16.11 instead of librte<?>.so.<LIBABIVER>.

We need to cut arbitrary long stings after the .so now and this would work
for any ABI version in LIBABIVER:
  $(Q)ln -s -f $< $(patsubst %.$(LIBABIVER),%,$@)
But using the following instead additionally allows to simplify the Make
File for the CONFIG_RTE_NEXT_ABI case.
  $(Q)ln -s -f $< $(shell echo $@ | sed 's/\.so.*/.so/')

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Reviewed-by: Jan Blunck <jblunck@infradead.org>
Tested-by: Jan Blunck <jblunck@infradead.org>