task_allocator: Use config switches instead of magic defines

Replace __HAVE_ARCH_TASK_ALLOCATOR and __HAVE_ARCH_THREAD_ALLOCATOR
with proper config switches.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/20120505150142.371309416@linutronix.de

arch/ia64/Kconfig

@@ -35,6 +35,8 @@ config IA64
 	select GENERIC_IOMAP
 	select GENERIC_SMP_IDLE_THREAD
 	select ARCH_INIT_TASK
+	select ARCH_TASK_STRUCT_ALLOCATOR
+	select ARCH_THREAD_INFO_ALLOCATOR
 	default y
 	help
 	  The Itanium Processor Family is Intel's 64-bit successor to

arch/ia64/include/asm/thread_info.h

@@ -54,8 +54,6 @@ struct thread_info {
 	},					\
 }
 
-#define __HAVE_ARCH_THREAD_INFO_ALLOCATOR
-
 #ifndef ASM_OFFSETS_C
 /* how to get the thread information struct from C */
 #define current_thread_info()	((struct thread_info *) ((char *) current + IA64_TASK_SIZE))
@@ -84,7 +82,6 @@ struct thread_info {
 #endif
 #define end_of_stack(p) (unsigned long *)((void *)(p) + IA64_RBS_OFFSET)
 
-#define __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
 #define alloc_task_struct_node(node)						\
 ({										\
 	struct page *page = alloc_pages_node(node, GFP_KERNEL | __GFP_COMP,	\