RFR(XS): 8219095: [testbug] Add @key headful to com/sun/java/swing/plaf/windows/AltFocusIssueTest.java

[Lindenmaier, Goetz]

Hi,

please review this tiny fix for the test. It fails in our headless
runs:
http://cr.openjdk.java.net/~goetz/wr19/8219095-headfulTest/01/

Best regards,
  Goetz.