ovsdb-idlc: Write a new-line at the end of "annotate" output.

ovsdb-idlc: Write a new-line at the end of "annotate" output.

Some tools do not like text files that lack a trailing new-line.  In
particular, Debian's dpkg-source utility complains about a missing new-line
in the file generated by ovsdb-idlc:

    dpkg-source: warning: file
    openvswitch-1.9.2+git20130605/lib/vswitch-idl.ovsidl has no final
    newline (either original or modified version)

This commit fixes the problem.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Ethan Jackson <ethan@nicira.com>