SSP: Check UINTPTR_TYPE to get uintptr_t type

default_stack_protect_guard calls

  lang_hooks.types.type_for_mode (ptr_mode, 1);

to get an integer type for __stack_chk_guard which is declared as a
global symbol of type uintptr_t.  For 32-bit systems, uintptr_t may
be either unsigned int or unsigned long int.  On 32-bit Darwin, we get

$ cat /tmp/x.c
__UINTPTR_TYPE__ __stack_chk_guard = 0x1000;
$ ./xgcc -B./ -S /tmp/x.c -m32
/tmp/x.c:1:18: error: conflicting types for ‘__stack_chk_guard’; have ‘long unsigned int’
    1 | __UINTPTR_TYPE__ __stack_chk_guard = 0x1000;
      |                  ^~~~~~~~~~~~~~~~~
cc1: note: previous declaration of ‘__stack_chk_guard’ with type ‘unsigned int’
$

since lang_hooks.types.type_for_mode returns unsigned int while Darwin's
uintptr_t is unsigned long int.  Update default_stack_protect_guard to
call unsigned_integer_tree_node_for_type with UINTPTR_TYPE to get unsigned
integer type for uintptr_t instead.

gcc/

	PR c/125226
	* targhooks.cc (default_stack_protect_guard): If UINTPTR_TYPE
	isn't NULL, call unsigned_integer_tree_node_for_type with
	UINTPTR_TYPE to get unsigned integer type for uintptr_t.
	* tree.cc (unsigned_integer_tree_node_for_type): New function.
	(build_common_tree_nodes): Call unsigned_integer_tree_node with
	SIZE_TYPE to get unsigned integer type for size_t.
	* tree.h (unsigned_integer_tree_node_for_type): New prototype.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>