SL-18289: Modify autobuild.xml to insert a CMaker architecture flag as well as the generator string for Windows builds

Implied 'branch' is now two different version-control systems behind

Part of his change was omly taking Release builds into account, the other
part from me made the same mistake.
Use a generator expression with a custom command to get the symlink the way
we want.

one genex that needed changing.
Interstingly add_custom_target will not complain about a file
that would never be declared as OUTPUT and thus is not really a
valid cmake build target.``

The include was preveiously declared for all platforms, but the Mac
package does not even ship this include directory. With the new way
cmake works this will lead to an error (which is good, so we don't
end with bogus include dirs).

Settings the startup project must come *after* add_subdirectory(newview). Only after this directory is added the target will be known and can be manipulated.

following promotion of DRTVWR-544