RFR: 8151847 rmic should support v53 classfiles

[Jonathan Gibbons]

Please review this one character change to have rmic support v53 class 
files:

JBS: https://bugs.openjdk.java.net/browse/JDK-8151847
Webrev: http://cr.openjdk.java.net/~jjg/8151847/webrev/
-- Jon