Change to Developer Studio 12.6 for building for Solaris at Oracle

It's time for Oracle to change the official compiler used for building OpenJDK on Solaris. The new version of Developer Studio will be 12.6 with the updates listed below and the build will happen on Solaris 11.3 SRU20.

developer/developerstudio-126/backend 12.6-1.0.0.1
developer/developerstudio-126/c++ 12.6-1.0.2.0
developer/developerstudio-126/cc 12.6-1.0.1.0
developer/developerstudio-126/dbx 12.6-1.0.0.1
developer/developerstudio-126/library/c++-libs 12.6-1.0.2.0
developer/developerstudio-126/library/c-libs 12.6-1.0.0.1
developer/developerstudio-126/library/f90-libs 12.6-1.0.0.1
developer/developerstudio-126/library/math-libs 12.6-1.0.0.1
developer/developerstudio-126/library/studio-gccrt 12.6-1.0.0.1
developer/developerstudio-126/studio-common 12.6-1.0.0.1
developer/developerstudio-126/studio-ja 12.6-1.0.0.1
developer/developerstudio-126/studio-legal 12.6-1.0.0.1
developer/developerstudio-126/studio-zhCN 12.6-1.0.0.1