Remove unnecessary sudo that causes failure to set up in Ubuntu 18.04

[janblumenkamp]

I tried to build AirSim on Ubuntu 18.04, but the setup.sh script failed at compiling and installing clang with the following error message:

[...]
Built target cxx_objects                                                                                                         
Built target cxxabi_objects                                                                                                                  
Built target cxxabi_shared                                                                                                         
Built target cxx_shared                                                                                                   
Built target cxx_static                                                                                           
Built target cxx                                                                                                   
Scanning dependencies of target cxx-headers                                                                               
CMake Error: Cannot open file for write: /auto/homes/jb2270/l310_project/AirSimClang/llvm-build/projects/libcxx/include/CMakeFiles/cxx-header
s.dir/depend.make.tmp                                                                                            
CMake Error: : System Error: Permission denied                                                                
projects/libcxx/include/CMakeFiles/cxx-headers.dir/build.make:70: recipe for target 'projects/libcxx/include/CMakeFiles/cxx-headers.dir/depen
d' failed                                                                                                                    
make[3]: *** [projects/libcxx/include/CMakeFiles/cxx-headers.dir/depend] Error 2                                       
CMakeFiles/Makefile2:14215: recipe for target 'projects/libcxx/include/CMakeFiles/cxx-headers.dir/all' failed          
make[2]: *** [projects/libcxx/include/CMakeFiles/cxx-headers.dir/all] Error 2                                         
CMakeFiles/Makefile2:14427: recipe for target 'projects/libcxx/lib/CMakeFiles/install-libcxx.dir/rule' failed           
make[1]: *** [projects/libcxx/lib/CMakeFiles/install-libcxx.dir/rule] Error 2                                              
Makefile:4255: recipe for target 'install-libcxx' failed                                                           
make: *** [install-libcxx] Error 2                                                                                 
[...]

The setup script itself weirdly did not really failed, it ran through anyways. Only when trying to run build.sh it complained with ERROR: clang++ and libc++ is necessary to compile AirSim and run it in Unreal engine. Please run setup.sh first. The reason for that is that for some reason the installation is attempted as sudo, but this does not really make sense and leads to the error message. Therefore I removed the sudo for all local operations. Both setup and build now runs successfully.

[madratman]

good catch, thanks!