Update to .NET Core Runtime 2.2.4 and SDK 2.2.106
    
    - Also update optflags patch to pass -D_GNU_SOURCE to make sure our
    build-time flags match the configure-time flags. Otherwise some
    functions like strerror_r() get different definitions.
    
    - Add a new patch to fix builds against newer versions of clang. Recent
    versions of clang refuse to compile assembly code that use hex constants
    with `0..h` prefix + suffix to mean a hex char. This syntax is also
    rejected by newer versions of GCC. Use plain `0x..` instead.
    
    - Renumber patches to make a little more sense: corefx is 100-series,
    coreclr is 200-series, core-setup is 300-series and cli is 400-series.
    
    - Add some scripts to automate the update-to-a-new-upstream-release
    process.
    
    - Sync spec file with other releases.