Change to using gopsutil for cross-OS process ops

Instead of trying to write out own code to do basic process
operations (e.g. checking if a PID is still running in a multi-OS
friendly manner), use shirou/gopsutil, a multi-platform library
that should abstract all the complexity away. Unlike our previous
approach on Windows, this one should actually work.

Signed-off-by: Matt Heon <mheon@redhat.com>

vendor/github.com/shoenig/go-m1cpu/incompatible.go

@@ -0,0 +1,53 @@
+//go:build !darwin || !arm64 || !cgo
+
+package m1cpu
+
+// IsAppleSilicon return false on this platform.
+func IsAppleSilicon() bool {
+	return false
+}
+
+// PCoreHZ requires darwin/arm64
+func PCoreHz() uint64 {
+	panic("m1cpu: not a darwin/arm64 system")
+}
+
+// ECoreHZ requires darwin/arm64
+func ECoreHz() uint64 {
+	panic("m1cpu: not a darwin/arm64 system")
+}
+
+// PCoreGHz requires darwin/arm64
+func PCoreGHz() float64 {
+	panic("m1cpu: not a darwin/arm64 system")
+}
+
+// ECoreGHz requires darwin/arm64
+func ECoreGHz() float64 {
+	panic("m1cpu: not a darwin/arm64 system")
+}
+
+// PCoreCount requires darwin/arm64
+func PCoreCount() int {
+	panic("m1cpu: not a darwin/arm64 system")
+}
+
+// ECoreCount requires darwin/arm64
+func ECoreCount() int {
+	panic("m1cpu: not a darwin/arm64 system")
+}
+
+// PCoreCacheSize requires darwin/arm64
+func PCoreCache() (int, int, int) {
+	panic("m1cpu: not a darwin/arm64 system")
+}
+
+// ECoreCacheSize requires darwin/arm64
+func ECoreCache() (int, int, int) {
+	panic("m1cpu: not a darwin/arm64 system")
+}
+
+// ModelName requires darwin/arm64
+func ModelName() string {
+	panic("m1cpu: not a darwin/arm64 system")
+}