Fixed MergeCommand to use Option instead of String (apache#5456)

Prior to apache#5450 the all option in the merge command
used an empty string for the short option. In 5450
we changed MergeCommand to use the Option.Builder,
which allows specifying a long option only, but
we didn't use the long option when getting the
option value which causes a ShellServerIT failure.
This changes the command line check to use the
Option object instead of the option string, which
is "", and the long option string.

Author: dlmarion

shell/src/main/java/org/apache/accumulo/shell/commands/MergeCommand.java

@@ -46,7 +46,7 @@ public int execute(final String fullCommand, final CommandLine cl, final Shell s
     if (cl.hasOption(forceOpt.getOpt())) {
       force = true;
     }
-    if (cl.hasOption(allOpt.getOpt())) {
+    if (cl.hasOption(allOpt)) {
       all = true;
     }
     if (cl.hasOption(sizeOpt.getOpt())) {