[VOL-4291] Rw-core updates for gRPC migration

Change-Id: I8d5a554409115b29318089671ca4e1ab3fa98810
diff --git a/vendor/golang.org/x/sys/unix/syscall_darwin_libSystem.go b/vendor/golang.org/x/sys/unix/syscall_darwin_libSystem.go
index f34c86c..53c9664 100644
--- a/vendor/golang.org/x/sys/unix/syscall_darwin_libSystem.go
+++ b/vendor/golang.org/x/sys/unix/syscall_darwin_libSystem.go
@@ -2,11 +2,12 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build darwin && go1.12
 // +build darwin,go1.12
 
 package unix
 
-import "unsafe"
+import _ "unsafe"
 
 // Implemented in the runtime package (runtime/sys_darwin.go)
 func syscall_syscall(fn, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)
@@ -24,10 +25,3 @@
 //go:linkname syscall_rawSyscall syscall.rawSyscall
 //go:linkname syscall_rawSyscall6 syscall.rawSyscall6
 //go:linkname syscall_syscallPtr syscall.syscallPtr
-
-// Find the entry point for f. See comments in runtime/proc.go for the
-// function of the same name.
-//go:nosplit
-func funcPC(f func()) uintptr {
-	return **(**uintptr)(unsafe.Pointer(&f))
-}