Add P3385 experimental clang compiler #92 #1

[zebullax]

Parent PR at compiler-explorer/clang-builder#92

[mattgodbolt]

These fields should be auto-generated by the pre commit hooks or the makefile target; there hopefully should be no need for manual steps

[zebullax]

These fields should be auto-generated by the pre commit hooks or the makefile target; there hopefully should be no need for manual steps

My setup here is throwing some errors on poetry due to proxy probably and other thingies.
I don't mind closing this and do the make thing from another less temperamental laptop, if that is preferred.