criu: arm -- Use conditional syscalls where needed

We're using general syscall-codes.h in criu itself
so make sure the headers we include do not override
system headers definitions.
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/arch/aarch64/include/asm/syscall-aux.h

-#define __NR_openat 56
+#ifndef __NR_openat
+# define __NR_openat 56
+#endif

criu/arch/arm/include/asm/syscall-aux.h

-#define __NR_mmap2 192
+#ifndef __NR_mmap2
+# define __NR_mmap2 192
+#endif
 
 #ifndef __ARM_NR_BASE
 # define __ARM_NR_BASE                   0x0f0000