Make the verbose take the level and return the level if valid.

This makes the verbose a single and removes the need to have the
logic of the test in the code.

linkers/rld.cpp

@@ -194,9 +194,9 @@ namespace rld
   }
 
   int
-  verbose ()
+  verbose (int level)
   {
-    return verbose_level;
+    return verbose_level && (verbose_level >= level) ? verbose_level : 0;
   }
 
   const std::string

linkers/rld.h

@@ -187,7 +187,7 @@ namespace rld
    * Return the verbose level. Setting the flag more than once raises the
    * level.
    */
-  int verbose ();
+  int verbose (int level = 0);
 
   /**
    * The version string.