x86: vdso ELF handling - use SELFMAG instead of numeric constant

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: akpm@linux-foundation.org
Cc: hpa@zytor.com
Cc: mingo@elte.hu
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/vdso/vdso32-setup.c

@@ -162,7 +162,7 @@ static __init void relocate_vdso(Elf32_Ehdr *ehdr)
 	Elf32_Shdr *shdr;
 	int i;
 
-	BUG_ON(memcmp(ehdr->e_ident, ELFMAG, 4) != 0 ||
+	BUG_ON(memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0 ||
 	       !elf_check_arch_ia32(ehdr) ||
 	       ehdr->e_type != ET_DYN);