RPMS: Also install C.py, JSON.py for vppapipgen.
RPMS: Also install C.py, JSON.py for vppapipgen.

When building plugins outside of the VPP tree, the vppapigen
tool requires the use of the C.py / JSON.py code.  To that end,
install it in /usr/share/vpp as referenced.

Change-Id: I457d58e7bde7140c7811fa0a93b4f44d1310784a
Signed-off-by: Jon Loeliger <2c20cf3f4bac0d9467d3fe2c932e4d1e1bc1f44c@netgate.com>

FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,vpp-dev/vpp,vpp-dev/vpp,chrisy/vpp,vpp-dev/vpp,vpp-dev/vpp,FDio/vpp,vpp-dev/vpp,vpp-dev/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,vpp-dev/vpp,chrisy/vpp,FDio/vpp