• 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.

Build: https://copr.fedorainfracloud.org/coprs/g/dotnet-sig/dotnet/build/882655/