bug#19466: 25.0.50; xref-find-def doesn't find C functions

[martin rudalics]

>  >> Debugger entered--Lisp error: (args-out-of-range "" 0)
>  >>    help-function-arglist(#[257 "\300\207" ["(No location)"] 2 "(No
>  >> location)\n\n(fn ##)"] preserve-names)
>  >>    eieio--defmethod(xref-location-group nil xref-bogus-location #[257
>  >> "\300\207" ["(No location)"] 2 "(No location)\n\n(fn ##)"])
>  >
>  > I'm sure Someone(tm) will fix that right away. :)
>
> For some value of "right away" :)

Meanwhile I additionally get:

  ELC      progmodes/xref.elc
`defgeneric' is an obsolete macro (as of 25.1); use `cl-defgeneric' instead.
`defgeneric' is an obsolete macro (as of 25.1); use `cl-defgeneric' instead.
`defmethod' is an obsolete macro (as of 25.1); use `cl-defmethod' instead.
`defgeneric' is an obsolete macro (as of 25.1); use `cl-defgeneric' instead.
`defmethod' is an obsolete macro (as of 25.1); use `cl-defmethod' instead.
`defgeneric' is an obsolete macro (as of 25.1); use `cl-defgeneric' instead.
`defmethod' is an obsolete macro (as of 25.1); use `cl-defmethod' instead.
`defgeneric' is an obsolete macro (as of 25.1); use `cl-defgeneric' instead.
`defmethod' is an obsolete macro (as of 25.1); use `cl-defmethod' instead.
`defgeneric' is an obsolete macro (as of 25.1); use `cl-defgeneric' instead.
`defmethod' is an obsolete macro (as of 25.1); use `cl-defmethod' instead.
`defgeneric' is an obsolete macro (as of 25.1); use `cl-defgeneric' instead.
`defmethod' is an obsolete macro (as of 25.1); use `cl-defmethod' instead.
`defgeneric' is an obsolete macro (as of 25.1); use `cl-defgeneric' instead.
`defmethod' is an obsolete macro (as of 25.1); use `cl-defmethod' instead.
`defgeneric' is an obsolete macro (as of 25.1); use `cl-defgeneric' instead.
`defmethod' is an obsolete macro (as of 25.1); use `cl-defmethod' instead.
`defgeneric' is an obsolete macro (as of 25.1); use `cl-defgeneric' instead.
`defmethod' is an obsolete macro (as of 25.1); use `cl-defmethod' instead.
`defgeneric' is an obsolete macro (as of 25.1); use `cl-defgeneric' instead.
`defmethod' is an obsolete macro (as of 25.1); use `cl-defmethod' instead.
`defgeneric' is an obsolete macro (as of 25.1); use `cl-defgeneric' instead.
`defmethod' is an obsolete macro (as of 25.1); use `cl-defmethod' instead.
`defgeneric' is an obsolete macro (as of 25.1); use `cl-defgeneric' instead.

In end of data:
progmodes/xref.el:625:1:Warning: the function `apropos-parse-pattern' is not
    known to be defined.

martin