runtime: use entersyscall in syscall_syscallX on Darwin
CL 197938 changed syscall* functions to call entersyscall, instead
of entersyscallblock. It missed syscall_syscallX, probably because
it was in sys_darwin_64.go, not sys_darwin.go like others. Change
that one as well.
Found during the review of CL 270380 (thanks Joel).
Change-Id: I0884fc766703f555a3895be332dccfa7d2431374
Reviewed-on: https://go-review.googlesource.com/c/go/+/286435
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>