build: Automated VPP build

build: Automated VPP build

VSPERF makefiles were updated to automatically download and compile
VPP. VPP will not be installed into the OS, but it will be executed
from VSPERF's src subdirectory. Thus underlying OS is not affected
by VPP build required by VSPERF. It also allows quick switch among
different versions of various tools used by VSPERF.

As part of this patch, VERIFY and MERGE CI jobs were updated to
build VPP and test it with basic set of integration tests.

JIRA: VSPERF-493

Change-Id: I958b9031c4fefc87c4c63a471d2ba1a0db1eaaa4
Signed-off-by: Martin Klozik <martinx.klozik@intel.com>
Reviewed-by: Al Morton <acmorton@att.com>
Reviewed-by: Christian Trautman <ctrautma@redhat.com>
Reviewed-by: Sridhar Rao <sridhar.rao@spirent.com>
Reviewed-by: Trevor Cooper <trevor.cooper@intel.com>