gdb/mi: Add -max-results parameter to some -symbol-info-* commands

gdb/mi: Add -max-results parameter to some -symbol-info-* commands

Adds a new parameter -max-results to -symbol-info-functions,
-symbol-info-variables, -symbol-info-types, and -symbol-info-modules.
This parameter limits the number of results returned.

This change still leaves -symbol-info-module-functions and
-symbol-info-module-variables always returning all results, fixing
these commands is slightly harder.

There's currently no mechanism for the user of these commands to know
if the result list has been truncated if you get back the maximum
number of results, so if there are exactly 10 functions and you call
'-symbol-info-functions --max-results 10' the reply would appear no
different than if you had 20 functions and called with a max of 10.
Right now, if you get back the maximum then you should assume that
there might be more results available.

One other thing to note is that the global_symbol_searcher::search by
default returns SIZE_MAX results, there's no longer a mechanism to
return an unlimited number of results, though hopefully this will not
be a huge issue.

gdb/ChangeLog:

	* mi/mi-symbol-cmds.c (mi_symbol_info): Take extra parameter, and
	add it into the search spec.
	(parse_max_results_option): New function.
	(mi_info_functions_or_variables): Parse -max-results flag and pass
	it to mi_symbol_info.
	(mi_cmd_symbol_info_modules): Likewise.
	(mi_cmd_symbol_info_types): Likewise.
	* symtab.c (global_symbol_searcher::add_matching_symbols): Change
	return type to bool, change result container into a set, and don't
	add new results if we have enough already.
	(global_symbol_searcher::add_matching_msymbols): Change return
	type to bool, and don't add new results if we have enough already.
	(sort_search_symbols_remove_dups): Delete.
	(global_symbol_searcher::search): Early exit from search loop when
	we have enough results.  Use a std::set to collect the results
	from calling add_matching_symbols.
	* symtab.h (global_symbol_searcher) <set_max_seach_results>: New
	member function.
	(global_symbol_searcher) <m_max_search_results>: New member
	variable.
	(global_symbol_searcher) <add_matching_symbols>: Update header
	comment and change return type to bool.
	(global_symbol_searcher) <add_matching_msymbols>: Update header
	comment and change return type to bool.

gdb/doc/ChangeLog:

	* doc/gdb.texinfo (GDB/MI Symbol Query): Add documentation of
	-max-results to some -symbol-info-* commands.

gdb/testsuite/ChangeLog:

	* gdb.mi/mi-sym-info.exp: Add tests for -max-results parameter.

Change-Id: I90a28feb55b388fb46461a096c5db08b6b0bd427