[8u] RFR: backport of 8231507: Update Apache Santuario (XML Signature) to version 2.1.4

[Fedor]

Hello everybody,

May I have a request backport of JDK-8231507?

Bug: https://bugs.openjdk.java.net/browse/JDK-8231507
webrev: http://cr.openjdk.java.net/~fijiol/8231507/webrev.8u.00/
testing:  jdk/test/com/sun/org/apache/xml/ jdk/test/javax/xml/crypto/dsig/

The code of library taken from jdk14 sources wasn't applied cleanly to 
jdk8u, so a sort of changes were done:

The changes made after copying files from jdk14:
http://cr.openjdk.java.net/~fijiol/8231507/webrev.8u.00/compare/with-14.html 
(raw diff: 
http://cr.openjdk.java.net/~fijiol/8231507/webrev.8u.00/compare/with-14.diff)

Several files were deleted.
The rest was taken "as is" from jdk14.

Thanks,
Fedor