Delete parse_flags/parse_flags_qcs

Delete parse_flags/parse_flags_qcs

Now that "thread/frame apply" have been converted to the gdb::option
framework, these functions are no longer used.

For a while, I thought about keeping the unit tests, by making a local
version of parse_flags_qcs in the unit tests file.  But all that would
really test that is used by GDB itself, is the validate_flags_qcs
function.  So in the end, I went through all the unit tests, and
converted any that wasn't already covered to gdb.base/options.exp
tests.  And those have all already been added in previous patches.

gdb/ChangeLog:
2019-06-13  Pedro Alves  <palves@redhat.com>

	* cli/cli-utils.c (parse_flags, parse_flags_qcs): Delete.
	* cli/cli-utils.h (parse_flags, parse_flags_qcs): Delete.
	* unittests/cli-utils-selftests.c (test_parse_flags)
	(test_parse_flags_qcs): Delete.
	(test_cli_utils): Don't call deleted functions.