RFR (JAXP): 8165116: redirect function is not allowed even with enableExtensionFunctions

[Joe Wang]

Hi,

Please review a fix for a missing check on the setting of property 
enableExtensionFunctions. Also closed the OutputStream after 
transformation is done.

JBS: https://bugs.openjdk.java.net/browse/JDK-8165116
webrev: http://cr.openjdk.java.net/~joehw/jdk9/8165116/webrev/

Thanks,
Joe