RFR: 8073385: Bad error message on parsing illegal character in XML attribute

[Aleksej Efimov]

Hi,
Please review the fix for corrupted error messages in XML parser. When 
the XML parser encounters illegal
character the message with incorrect data is generated:
An invalid XML character (Unicode: 0x{2}) was found in the value of 
attribute "{1}" and element is "0".
But it should be like:
An invalid XML character (Unicode: 0x0) was found in the value of 
attribute "attTest" and element is "topElement".
The fix repairs the message generation and it is similar to the code in 
Apache Xerces project.
Testing: JTREG and JPRT tests (with new one) showed no failures with XML 
related tests.

Thanks,
Aleksej

[1] JBS: https://bugs.openjdk.java.net/browse/JDK-8073385
[2] Webrevs:
     jaxp: http://cr.openjdk.java.net/~aefimov/8073385/9/00/jaxp/
     jdk: http://cr.openjdk.java.net/~aefimov/8073385/9/00/jdk/