libmain: add progress bar with multiple status lines

Add the log-formats `multiline` and `multiline-with-logs` which offer
multiple current active building status lines.

Change-Id: Idd8afe62f8591b5d8b70e258c5cefa09be4cab03

src/libutil/logging.hh

@@ -114,6 +114,9 @@ public:
 
     virtual void setPrintBuildLogs(bool printBuildLogs)
     { }
+
+    virtual void setPrintMultiline(bool printMultiline)
+    { }
 };
 
 /**