Disallow flags with extra characters appended

[Jesper Wilhelmsson]

Hi,

Today some (not all) flags are accepted even though they have random characters 
appended to them. Some examples are -Xconcgc, -Xcomp, -Xboundthreads, 
-XX:+AlwaysTenure etc which will also be accepted when written for instance 
-Xconcgcnoway, -Xcomposer, -Xboundthreadstodogs or -XX:+AlwaysTenureAtBlueMoon

There is a potential problem here since we will also accept things like 
-XX:+ExtendedDTraceProbes-XX:+UseG1GC without saying a word (and of course 
without running with G1).

I have a suggestion for a fix here:
http://cr.openjdk.java.net/~jwilhelm/commandLineFlag/webrev.00/

Would this be an acceptable solution?

I couldn't find one, but since this has been around for quite some time I wonder 
if there is a bug for this already. If not I'll create one.

Thanks,
/Jesper