Read the proc status file when PID is given for metrics purpose.

To measure the MaxRSS memory correctly, read the proc status file
under /proc/<pid>/status and extract the MaxRSS value from it. The
implementation is only available for Linux based distributions.

Bug: b/169453825
Test: go test
Change-Id: I32e3068fee7447f9ef5dfb5a8d8dcb6934e0af23

ui/metrics/proc/status_darwin.go

@@ -0,0 +1,11 @@
+package proc
+
+import (
+	"android/soong/finder/fs"
+)
+
+// NewProcStatus returns a zero filled value of ProcStatus as it
+// is not supported for darwin distribution based.
+func NewProcStatus(pid int, _ fs.FileSystem) (*ProcStatus, error) {
+	return &ProcStatus{}, nil
+}