In the past we have been using misc gcc compilers on Solaris. These
compilers are no longer able to build the server, so we switched to
Oracle Studio. There is now a port of gcc 7 available as a native
compiler in Solaris, both for Intel and Sparc.

Remove obsolete/wrong cmake code for gcc on Solaris, use:
  /usr/bin/g++ --version
  g++ (GCC) 7.3.0
which has proper library support on Solaris 11.4

The patch also removes obsolete cmake code for "dual" build where we used to:
- build the server with a non-native version of gcc
- build the client libraries with Oracle Studio.

================
client/dump/CMakeLists.txt

Remove disabling of mysqlpunp when using Studio compiler. This was
disabled earlier due to missing features in older versions of Studio.

Remove obsolete cmake code for silencing warnings from Boost. Boost header
files are now #included as "system" so no warnings are generated.

Remove property RUNTIME_OUTPUT_DIRECTORY for the mysqlpump executable.
This was used earlier for the "dual" build, building the server with gcc,
client with Studio.
================
cmake/build_configurations/compiler_options.cmake

Remove obsolete version checks for Studio compiler. Add explicit -std=c++03

================
cmake/build_configurations/mysql_release.cmake

Remove obsolete cmake code for dual gcc/Studio build.

================
cmake/os/SunOS.cmake

Raise minimum compiler version for both gcc and Studio.

================
configure.cmake

Remove obsolete cmake code for supporting older C++ libraries.
We now only support -std=c++03

Remove obsolete cmake code for supporting non-native gcc compilers.

================
scripts/CMakeLists.txt

Remove obsolete cmake code for dual gcc/Studio build.

================
unittest/gunit/CMakeLists.txt

Remove obsolete check for unsupported version of Studio.

Change-Id: Ib286460257a881ee54f485ee83a233585d258b7c