RFR [XS]: 8236274: remove obsolete -d2Zi+ debug flag in MSVC builds

[Baesken, Matthias]

Hello, please review this small MSVC related change .

The MSVC based builds still have the old flag -d2Zi+ set; this is  an undocumented flag , the name of the flag  for enhanced optimized debugging  is since VS2013 -Zo .
However the flag (-Zo)  is enabled by default for a long time , so   the old  undocumented version  of it ("-d2Zi+") should be  removed completely.


See the VS2017 documentation :
https://docs.microsoft.com/en-us/cpp/build/reference/zo-enhance-optimized-debugging?view=vs-2017

"The /Zo option is enabled by default in Visual Studio when you specify debugging information with /Zi or /Z7. Specify /Zo- to explicitly disable this compiler option.
The /Zo switch is available starting in Visual Studio 2013 Update 3, and it replaces the previously undocumented /d2Zi+ switch."


Bug/webrev :
https://bugs.openjdk.java.net/browse/JDK-8236274

http://cr.openjdk.java.net/~mbaesken/webrevs/8236274.0/


Thanks, Matthias