RFR(M): 8245226: Clean-up FlagSetting and remove misuse.

[Patric Hedlin]

Dear all,

I would like to ask for help to review the following change/update:

Issue:  https://bugs.openjdk.java.net/browse/JDK-8245226
Webrev: http://cr.openjdk.java.net/~phedlin/tr8245226/


FlagSetting is sometimes used as a general mechanism for local 
save/modify and restore. This is not the intention (it should work as a 
red-flag when modifying debug options). Instead, use a general mechanism 
in these cases (introduced in here), and preserve FlagSetting for its 
intended purpose (including clean-up).


Testing: hs-tier1-3


Best regards,
Patric