Build a LLVM9 bootstrapping shard (#317)

* apply patches automatically

* add LLVM9

* hopefully we only need the libcxx patch?

* turn off sanitizers on musl

* libcxx should use crt

Author: vchuravy

0_RootFS/LLVMBootstrap@6/bundled/patches/llvm6_compiler_rt_musl.patch renamed to 0_RootFS/LLVMBootstrap@6/bundled/patches/0001-llvm6_compiler_rt_musl.patch

@@ -0,0 +1,11 @@
+# Include everything common between our LLVM versions (That's a lot)
+include("../llvm_common.jl")
+
+# Build the tarballs, then upload to Yggdrasil releases
+
+name = "LLVMBootstrap"
+version = v"9.0.1"
+sources, script, products, dependencies = llvm_build_args(;version=version) 
+build_info = build_tarballs(ARGS, name, version, sources, script, [host_platform], products, dependencies; skip_audit=true)
+upload_and_insert_shards("JuliaPackaging/Yggdrasil", name, version, build_info)
+