Fix Source0/1: %{version} had rc_ver twice
    
    ```
    Version:        %{maj_ver}.%{min_ver}.%{patch_ver}%{?rc_ver:~rc%{rc_ver}}
    Source0:        https://github.com/llvm/llvm-project/releases/download/llvmorg-%{version}%{?rc_ver:-rc%{rc_ver}}/%{llvm_srcdir}.tar.xz
    Source0:        https://github.com/llvm/llvm-project/releases/download/llvmorg-%{version}%{?rc_ver:-rc%{rc_ver}}/%{llvm_srcdir}.tar.xz.sig
    ```
    
    This produces a non existing URLs:
    
    https://github.com/llvm/llvm-project/releases/download/llvmorg-13.0.0~rc1-rc1/llvm-13.0.0rc1.src.tar.xz
    https://github.com/llvm/llvm-project/releases/download/llvmorg-13.0.0~rc1-rc1/llvm-13.0.0rc1.src.tar.xz.sig
    
    The correct URLs would be
    
    https://github.com/llvm/llvm-project/releases/download/llvmorg-13.0.0-rc1/llvm-13.0.0rc1.src.tar.xz
    https://github.com/llvm/llvm-project/releases/download/llvmorg-13.0.0-rc1/llvm-13.0.0rc1.src.tar.xz.sig