RFR: JDK-8232770 Enable more warnings on solaris studio

[Magnus Ihse Bursie]

As a part of the ongoing process of cleaning up and improving our 
handling of warnings, the time has now come to the solstudio compiler. 
(I know this is not the most relevant of compilers, but I actually 
started out with the warning cleanup project on solstudio, since it's a 
simple, but limited, compiler in terms of options. So this is an old 
personal branch that I'm finally bringing in to mainline.)

Just as we have done with gcc (-Wall -Wextra), we should increase the 
general warning levels on solstudio, and then -- if needed -- disable 
individual warnings. Warnings should be disabled on a per-library level 
if they indicate real issues that should be fixed, or globally if they 
are deemed not relevant for the project as a whole. (Unfortunately, for 
solstudio, some warnings that really should be fixed applied to just 
about every library, and for sanity's sake I had to disable them globally.)

I also deemed a few warnings that had previously been individually 
disabled, to be dumb enough (or at least unsuitable to us) to warrant 
global disabling.

I intend to open separate bugs on the owners of the native libraries 
where new warnings have been disabled, since I believe they point to 
real bugs, or at least sloppy programming practices, and should be 
addressed.

Bug: https://bugs.openjdk.java.net/browse/JDK-8232770
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8232770-enable-more-solstudio-warnings/webrev.01

/Magnus