Print a status message when starting ninja

This way we don't appear hung at:

  No need to regenerate ninja file

Change-Id: I8dbdaa2c1b1c5a6a73187d0e6061f363b62e10c9
Fixes: 122251150
Test: m nothing
diff --git a/ui/build/ninja.go b/ui/build/ninja.go
index c8f19d1..ab15e86 100644
--- a/ui/build/ninja.go
+++ b/ui/build/ninja.go
@@ -97,6 +97,7 @@
 		}
 	}()
 
+	ctx.Status.Status("Starting ninja...")
 	cmd.RunAndPrintOrFatal()
 }
 
diff --git a/ui/status/status.go b/ui/status/status.go
index c851d7f..46ec72e 100644
--- a/ui/status/status.go
+++ b/ui/status/status.go
@@ -260,6 +260,10 @@
 	}
 }
 
+func (s *Status) Status(msg string) {
+	s.message(StatusLvl, msg)
+}
+
 type toolStatus struct {
 	status *Status