Fix PR python/20129 - use of non-existing variable

Fix PR python/20129 - use of non-existing variable

PR python/20129 concerns the error message one gets from a command
like "disable frame-filter global NoSuchFilter".  Currently this
throws a second, unexpected, exception due to the use of a
non-existing variable named "name".

This patch adds regression tests and fixes a couple of spots to use
the correct variable name.

Built and regtested on x86-64 Fedora 23.

2016-06-29  Tom Tromey  <tom@tromey.com>

	PR python/20129:
	* python/lib/gdb/command/frame_filters.py (_do_enable_frame_filter)
	(SetFrameFilterPriority._set_filter_priority): Use "frame_filter",
	not "name".

2016-06-29  Tom Tromey  <tom@tromey.com>

	PR python/20129:
	* gdb.python/py-framefilter.exp: Add tests for setting priority
	and disabling of non-existent frame filter.