Add GetMemIgnoringCGroups to fake sigar interface

[#179517901] Update Bosh Agent to correctly report memory used in `bosh vms --vitals` and related code paths, and publish new stemcells

Signed-off-by: Kenneth Lakin <klakin@vmware.com>

fakes/fake_sigar.go

@@ -10,8 +10,9 @@ type FakeSigar struct {
 	LoadAverage    sigar.LoadAverage
 	LoadAverageErr error
 
-	Mem    sigar.Mem
-	MemErr error
+	Mem                sigar.Mem
+	MemIgnoringCGroups sigar.Mem
+	MemErr             error
 
 	Swap    sigar.Swap
 	SwapErr error
@@ -62,6 +63,10 @@ func (f *FakeSigar) GetMem() (sigar.Mem, error) {
 	return f.Mem, f.MemErr
 }
 
+func (f *FakeSigar) GetMemIgnoringCGroups() (sigar.Mem, error) {
+	return f.MemIgnoringCGroups, f.MemErr
+}
+
 func (f *FakeSigar) GetSwap() (sigar.Swap, error) {
 	return f.Swap, f.SwapErr
 }