CC: Add /builtin to include paths in CC1 instead of Native.

divine/cc/cc1.cpp

@@ -146,6 +146,7 @@ namespace divine::cc
                                                 "-fdiagnostics-show-option",
                                                 "-fcolor-diagnostics",
                                                 // "-o", "test.o",
+                                                "-isystem", "/builtin"
                                                 };
         bool exceptions = type == FileType::Cpp || type == FileType::CppPreprocessed;
 

divine/cc/native.cpp

@@ -38,7 +38,6 @@ namespace divine::cc
                          driver->commonFlags.begin(),
                          driver->commonFlags.end() );
         _clang.allowIncludePath( "/" );
-        _po.opts.insert( _po.opts.end(), { "-isystem", "/builtin" } );
     }
 
     int Native::compile_files()