arch: Sanitize headers inclusion in arch/x86/crtools.c

 - For NT_X86_XSTATE we need a system elf.h
 - Drop duplicated parasite-syscall.h
 - Organize headers in the way
    - system headers
    - asm headers
    - regular headers
    - protobuf stuff
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

arch/x86/crtools.c

 #include <string.h>
 #include <unistd.h>
+#include <elf.h>
 
+#include "asm/processor-flags.h"
 #include "asm/types.h"
 #include "asm/fpu.h"
+
 #include "compiler.h"
 #include "ptrace.h"
-#include "asm/processor-flags.h"
-#include "protobuf.h"
-#include "protobuf/core.pb-c.h"
-#include "protobuf/creds.pb-c.h"
 #include "parasite-syscall.h"
+#include "restorer.h"
 #include "syscall.h"
 #include "log.h"
 #include "util.h"
 #include "cpu.h"
-#include "elf.h"
-#include "parasite-syscall.h"
-#include "restorer.h"
+
+#include "protobuf.h"
+#include "protobuf/core.pb-c.h"
+#include "protobuf/creds.pb-c.h"
 
 /*
  * Injected syscall instruction