Update llvm9 to version 9.0.1 / rev 19 via SR 851113
https://build.opensuse.org/request/show/851113
by user aaronpuchert + dimstar_suse
- Add patch Fix-big-endian-miscompile-of-bitcast-zex.patch
to fix miscompilations with rustc 1.43 that lead to LTO failures
(bsc#1173202)