Add x86_64 perfmon tables

The license issue is resolved, so we can package the .json
files. Added to the vpp-dev package in .tar.xz form, which saves a lot
of space.

Updated the perfmon error log entry: tell folks where to find the
compressed tarball, and how to extract it.

Change-Id: I3ed351fbf154cc3ba22d5f9c666acff77a2a14cf
Signed-off-by: Dave Barach <dave@barachs.net>

build-root/scripts/find-dev-contents

@@ -28,8 +28,8 @@ do
     fi
 done        
 
-# Perf monitor .json files
-for i in $(find ${1}/vpp/share/vpp/plugins/perfmon -name *.json -type f -print); do
+# Perf monitor .json tarball
+for i in $(find ${1}/vpp/share/vpp/plugins/perfmon -name *.tar.xz -type f -print); do
     echo ../${i} /usr/share/vpp/plugins/perfmon >> ${2}
 done