[10] Review request: 8191712: javapackager help output has a typo

[victor.drozdov at oracle.com]

Alexander,

Please review my changes about fixing typos in javapackager help output 
and jdk/packager/builders/mac/MacAppImageBuilder.

The fix also corrected the typo from JDK-8189339

JIRA: https://bugs.openjdk.java.net/browse/JDK-8191712
Webrev: http://cr.openjdk.java.net/~vdrozdov/JDK-8191712/webrev.00/

--Victor