C++-ify bp_location

C++-ify bp_location

Philippe noticed a memory leak coming from ada_catchpoint_location --
it was not freeing the "function_name" member from its base class:

==14141== 114 bytes in 4 blocks are definitely lost in loss record 1,055 of 3,424
==14141==    at 0x4C2BE6D: malloc (vg_replace_malloc.c:309)
==14141==    by 0x405107: xmalloc (common-utils.c:44)
==14141==    by 0x7563F9: xstrdup (xstrdup.c:34)
==14141==    by 0x3B82B3: set_breakpoint_location_function(bp_location*, int) (breakpoint.c:7156)
==14141==    by 0x3C112B: add_location_to_breakpoint(breakpoint*, symtab_and_line const*) (breakpoint.c:8609)
==14141==    by 0x3C127A: init_raw_breakpoint(breakpoint*, gdbarch*, symtab_and_line, bptype, breakpoint_ops const*) (breakpoint.c:7187)
==14141==    by 0x3C1B52: init_ada_exception_breakpoint(breakpoint*, gdbarch*, symtab_and_line, char const*, breakpoint_ops const*, int, int, int) (breakpoint.c:11262)
==14141==    by 0x381C2E: create_ada_exception_catchpoint(gdbarch*, ada_exception_catchpoint_kind, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, int, int, int) (ada-lang.c:13255)

This patch fixes the problem by further C++-ifying bp_location.  In
particular, bp_location_ops is now removed, and the "dtor" function
pointer is replaced with an ordinary destructor.

gdb/ChangeLog
2019-02-15  Philippe Waroquiers  <philippe.waroquiers@skynet.be>
	    Tom Tromey  <tromey@adacore.com>

	* breakpoint.c (~bp_location): Rename from bp_location_dtor.
	(bp_location_ops): Remove.
	(base_breakpoint_allocate_location): Update.
	(free_bp_location): Update.
	* ada-lang.c (class ada_catchpoint_location)
	<ada_catchpoint_location>: Remove ops parameter.
	(ada_catchpoint_location_dtor): Remove.
	(ada_catchpoint_location_ops): Remove.
	(allocate_location_exception): Update.
	* breakpoint.h (struct bp_location_ops): Remove.
	(class bp_location) <bp_location>: Remove bp_location_ops
	parameter.
	<~bp_location>: Add destructor.
	<ops>: Remove.