JDK7 Build 31 and Solaris builds with Sun Studio 12

[Kelly O'Hair]

Just an update...

The following changesets integrated into Build 31 should allow the
OpenJDK7 to be built with Sun Studio 12 (SS12) compilers on Solaris
10 and above.

    * http://hg.openjdk.java.net/jdk7/jdk7/rev/cda4ce5a6494
    * http://hg.openjdk.java.net/jdk7/jdk7/jdk/rev/f9467b4496dc
    * http://hg.openjdk.java.net/jdk7/jdk7/hotspot/rev/a49545cab84a
    * http://hg.openjdk.java.net/jdk7/jdk7/hotspot/rev/86658812ca35

SS12 needs to be in your PATH and also referred to with ALT_COMPILER_PATH.

We are not officially changing to the SS12 compilers just yet, we still
need to run some performance measurements and do some testing of Solaris
JDK's built with SS12. Once those results are in, and are positive, then
SS12 will be validated in our view and we will make a few minor changes
to the Makefiles to "expect at least SS12" and warn otherwise.

The Sun Studio Express compiler is a SS12+ compiler as I understand it, and
should work also, but it's also somewhat of a moving target, so anyone
using it needs to understand that there is some risk here.
Internally we try and lock down the compiler version once we have validated it.

-kto