Get rid of VEC (mem_region)

This patch removes VEC (mem_region).  Doing so requires touching a lot
of little things here and there.

The fields in mem_attrib are now initialized during construction.  The
values match those that were in default_mem_attrib (now removed).
unknown_mem_attrib is also removed, and replaced with a static method
(mem_attrib::unknown) that returns the equivalent.

mem_region is initialized in a way similar to mem_region_init (now
removed) did.

I found the organization of mem_region_list and target_mem_region_list a
bit confusing.  Sometimes mem_region_list points to the same vector as
target_mem_region_list (and therefore does not own it), and sometimes
(when the user manually edits the mem regions) points to another vector,
and in this case owns it.  To avoid this ambiguity, I think it is
simpler to have two vectors, one for target-defined regions and one for
user-defined regions, and have mem_region_list point to one or the
other.  There are now no vector objects dynamically allocated, both are
static.

The make-target-delegates script does not generate valid code when a
target method returns a type with a parameter list.  For this reason, I
created a typedef (mem_region_vector) that's only used in the target_ops
structure.  If you speak perl, you are welcome to improve the script!

Regtested on the buildbot.

gdb/ChangeLog:

	* memattr.h: Don't include vec.h.
	(struct mem_attrib): Initialize fields.
	<unknown>: New static method.
	(struct mem_region): Add constructors, operator<, initialize
	fields.
	* memattr.c: Include algorithm.
	(default_mem_attrib, unknown_mem_attrib): Remove.
	(user_mem_region_list): New global.
	(target_mem_region_list, mem_region_list): Change type to
	std::vector<mem_region>.
	(mem_use_target): Now a function.
	(target_mem_regions_valid): Change type to bool.
	(mem_region_lessthan, mem_region_cmp, mem_region_init): Remove.
	(require_user_regions): Adjust.
	(require_target_regions): Adjust.
	(create_mem_region): Adjust.
	(lookup_mem_region): Adjust.
	(invalidate_target_mem_regions): Adjust.
	(mem_clear): Rename to...
	(user_mem_clear): ... this, and adjust.
	(mem_command): Adjust.
	(info_mem_command): Adjust.
	(mem_enable, enable_mem_command, mem_disable,
	disable_mem_command): Adjust.
	(mem_delete): Adjust.
	(delete_mem_command): Adjust.
	* memory-map.h (parse_memory_map): Return an std::vector.
	* memory-map.c (parse_memory_map): Likewise.
	(struct memory_map_parsing_data): Add constructor.
	<memory_map>: Point to std::vector.
	(memory_map_start_memory): Adjust.
	(memory_map_end_memory): Adjust.
	(memory_map_end_property): Adjust.
	(clear_result): Remove.
	* remote.c (remote_memory_map): Return an std::vector.
	* target-debug.h (target_debug_print_VEC_mem_region_s__p):
	Remove.
	(target_debug_print_mem_region_vector): New.
	* target-delegates.c: Regenerate.
	* target.h (mem_region_vector): New typedef.
	(to_memory_map): Return mem_region_vector.
	(target_memory_map): Return an std::vector.
	* target.c (target_memory_map): Return an std::vector.
	(flash_erase_command): Adjust.

gdb/memory-map.h

@@ -25,8 +25,7 @@
 
 /* Parses XML memory map passed as argument and returns the memory
    regions it describes.  On any error, emits error message and
-   returns 0.  Does not throw.  Ownership of result is passed to the
-   caller.  */
-VEC(mem_region_s) *parse_memory_map (const char *memory_map);
+   return an empty vector.  Does not throw.  */
+std::vector<mem_region> parse_memory_map (const char *memory_map);
 
 #endif