selftests/bpf: Emit nop1,nop5 instructions for x86_64 usdt probe#15

Syncing latest usdt.h change [1].

Now that we have no5 optimization support in kernel, let's emit
nop,nop5 for usdt probe. We leave it up to the library to use
desirable nop instruction.

[1] libbpf/usdt#15
Signed-off-by: Jiri Olsa <jolsa@kernel.org>

Author: olsajiri

tools/testing/selftests/bpf/usdt.h

@@ -312,6 +312,8 @@ struct usdt_sema { volatile unsigned short active; };
 #ifndef USDT_NOP
 #if defined(__ia64__) || defined(__s390__) || defined(__s390x__)
 #define USDT_NOP			nop 0
+#elif defined(__x86_64__)
+#define USDT_NOP                       .byte 0x90, 0x0f, 0x1f, 0x44, 0x00, 0x0 /* nop, nop5 */
 #else
 #define USDT_NOP			nop
 #endif