Vendor psutils and remove neko

plugins/system/ps/host/host_darwin_amd64.go

@@ -0,0 +1,19 @@
+// Created by cgo -godefs - DO NOT EDIT
+// cgo -godefs types_darwin.go
+
+package host
+
+type Utmpx struct {
+	User      [256]int8
+	Id        [4]int8
+	Line      [32]int8
+	Pid       int32
+	Type      int16
+	Pad_cgo_0 [6]byte
+	Tv        Timeval
+	Host      [256]int8
+	Pad       [16]uint32
+}
+type Timeval struct {
+	Sec int32
+}