SVN to Git Conversion

[James Clarke]

Hi all,
After seeing Sylvestre apologise to Adrian for the continued use of SVN for
LLVM's packaging (and hating the experience myself every time I go to look at
something in ViewVC), I decided to go and fix this, and created [0], which has
a series of scripts to do the different stages of the Git to Subversion
conversion process for:

 * emscripten
 * iwyu
 * libcxx
 * llvm-defaults
 * llvmlite
 * llvm-toolchain
 * openmprtl

I have done some level of verification that the history looks sane,
predominantly by looking at the commit tree, so it's probably in a good enough
state to use, but if I've missed any packages which are still being maintained
they may or may not just work when added to the rules file.

I have pushed the results to https://salsa.debian.org/jrtc27/PACKAGE as well.
The scripts should be reproducible, as all the metadata comes from the SVN
commits, so you should end up with the same commit hashes as me. I'll let you
decide how (and if) you want to proceed, but I'm happy to help out further in
the process.

Regards,
James

[0] https://salsa.debian.org/jrtc27/pkg-llvm-svn2git