Allow enabling/disabling breakpoint location ranges

Allow enabling/disabling breakpoint location ranges

When a breakpoint has multiple locations, like e.g.:

 Num  Type       Disp Enb  Address    What
 1    breakpoint keep y    <MULTIPLE>
 1.1                  y    0x080486a2 in void foo<int>()...
 1.2                  y    0x080486ca in void foo<double>()...
 [....]
 1.5                  y    0x080487fa in void foo<long>()...

it's possible to enable/disable the individual locations using the
'<breakpoint_number>.<location_number>' syntax, like e.g.:

 (gdb) disable 1.2 1.3 1.4 1.5

That's inconvenient when you have a long list of locations to disable,
however.

This patch adds shorthand for the above, by making it possible to
specify a range of locations with the following syntax (similar to
thread id ranges):

 <breakpoint_number>.<first_location_number>-<last_location_number>

For example, the command above can now be simplified to:

 (gdb) disable 1.2-5

gdb/ChangeLog:
2017-11-07  Xavier Roirand  <roirand@adacore.com>
	    Pedro Alves  <palves@redhat.com>

	* breakpoint.c (map_breakpoint_number_range): New, factored out
	from ...
	(map_breakpoint_numbers): ... here.
	(find_location_by_number): Change parameters from string to
	breakpoint number and location.
	(extract_bp_number_and_location): New function.
	(enable_disable_bp_num_loc)
	(enable_disable_breakpoint_location_range)
	(enable_disable_command): New functions, factored out ...
	(enable_command, disable_command): ... these functions, and
	adjusted to support ranges.
	* NEWS: Document enable/disable breakpoint location range feature.

gdb/doc/ChangeLog:
2017-11-07  Xavier Roirand  <roirand@adacore.com>
	    Pedro Alves  <palves@redhat.com>

	* gdb.texinfo (Set Breaks): Document support for breakpoint
	location ranges in the enable/disable commands.

gdb/testsuite/ChangeLog:
2017-11-07  Xavier Roirand  <roirand@adacore.com>
	    Pedro Alves  <palves@redhat.com>

	* gdb.base/ena-dis-br.exp: Add reference to
	gdb.cp/ena-dis-br-range.exp.
	* gdb.cp/ena-dis-br-range.exp: New file.
	* gdb.cp/ena-dis-br-range.cc: New file.