Output RST comment with enough linefeeds.

Empty RST comments need an extra empty line afterwards, re this output
from rst2man:

    (WARNING/2) Explicit markup ends without a blank line; unexpected unindent

lib/libvcc/vmodtool.py

@@ -803,7 +803,7 @@ for suf in ("", ".man"):
 		fp.write("..\n")
 		fp.write(".. This file was autogenerated by %s. DO NOT EDIT!\n" %
 			 basename(__file__))
-		fp.write("..\n")
+		fp.write("..\n\n")
 
 		vx[0].doc_dump(fp, suf)