[binutils-gdb] Use gdbpy_ref in py-prettyprint.c

[sergiodj+buildbot at sergiodj dot net]

*** TEST RESULTS FOR COMMIT 0700aea50c7a77d7908868373d0f9644b0ece29c ***

Author: Tom Tromey <tom@tromey.com>
Branch: master
Commit: 0700aea50c7a77d7908868373d0f9644b0ece29c

Use gdbpy_ref in py-prettyprint.c

This changes several functions in py-prettyprint.c to use
gdbpy_ref.

2017-01-10  Tom Tromey  <tom@tromey.com>

	* python/py-prettyprint.c (search_pp_list)
	(find_pretty_printer_from_objfiles)
	(find_pretty_printer_from_progspace)
	(find_pretty_printer_from_gdb, find_pretty_printer)
	(gdbpy_get_display_hint, gdbpy_get_varobj_pretty_printer): Use
	gdbpy_ref.