golang/xenlight: standardize generated code comment
There is a standard format for generated Go code header comments, as set
by [1]. Modify gengotypes.py to follow this standard, and use the
additional
// source: <IDL file basename>
convention used by protoc-gen-go.
This change is motivated by the fact that since
41aea82de2, the comment
would include the absolute path to libxl_types.idl, therefore creating
unintended diffs when generating code across different machines. This
approach fixes that problem.
[1] https://github.com/golang/go/issues/13560
Signed-off-by: Nick Rosbrook <rosbrookn@ainfosec.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>