[IA64] rename _bss to __bss_start

Rename _bss to __bss_start as on other architectures. That makes it
possible to use the <linux/sections.h> instead of own declarations. Also
add __bss_stop because that symbol exists on other architectures.

Signed-off-by: Bernhard Walle <[e-mail]>
Cc: "Luck, Tony" <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Tony Luck <[e-mail]>

arch/ia64/hp/sim/boot/bootloader.lds

···
   .sdata     : { *(.sdata) }
   _edata  =  .;
 
-  _bss = .;
+  __bss_start = .;
   .sbss      : { *(.sbss) *(.scommon) }
   .bss       : { *(.bss) *(COMMON) }
   . = ALIGN(64 / 8);
+  __bss_stop = .;
   _end = . ;
 
   /* Stabs debugging sections.  */

arch/ia64/kernel/setup.c

···
 	.name	= "Kernel bss",
 	.flags	= IORESOURCE_BUSY | IORESOURCE_MEM
 };
-extern char _text[], _end[], _etext[], _edata[], _bss[];
 
 unsigned long ia64_max_cacheline_size;
 
···
 	code_resource.end   = ia64_tpa(_etext) - 1;
 	data_resource.start = ia64_tpa(_etext);
 	data_resource.end   = ia64_tpa(_edata) - 1;
-	bss_resource.start  = ia64_tpa(_bss);
+	bss_resource.start  = ia64_tpa(__bss_start);
 	bss_resource.end    = ia64_tpa(_end) - 1;
 	efi_initialize_iomem_resources(&code_resource, &data_resource,
 			&bss_resource);

arch/ia64/kernel/vmlinux.lds.S

···
   .sdata : AT(ADDR(.sdata) - LOAD_OFFSET)
 	{ *(.sdata) *(.sdata1) *(.srdata) }
   _edata  =  .;
-  _bss = .;
+  __bss_start = .;
   .sbss : AT(ADDR(.sbss) - LOAD_OFFSET)
 	{ *(.sbss) *(.scommon) }
   .bss : AT(ADDR(.bss) - LOAD_OFFSET)
 	{ *(.bss) *(COMMON) }
+  __bss_stop = .;
 
   _end = .;