Rollup merge of rust-lang#80796 - cuviper:llvm-11.0.1, r=nikic

Update to LLVM 11.0.1

This updates to a new LLVM branch, rebased on the upstream `llvmorg-11.0.1`. All our patches applied cleanly except the fortanix unwind changes, which just needed a small adjustment in cmake files.

r? `@nikic`
Fixes rust-lang#73722

Author: Dylan-DPC

.gitmodules

@@ -37,7 +37,7 @@
 [submodule "src/llvm-project"]
 	path = src/llvm-project
 	url = https://github.com/rust-lang/llvm-project.git
-	branch = rustc/11.0-2020-10-12
+	branch = rustc/11.0-2021-01-05
 [submodule "src/doc/embedded-book"]
 	path = src/doc/embedded-book
 	url = https://github.com/rust-embedded/book.git

src/llvm-project

@@ -2,8 +2,9 @@
 // Tests that we can compare various kinds of extern fn signatures.
 #![allow(non_camel_case_types)]
 
-extern fn voidret1() {}
-extern fn voidret2() {}
+// `dbg!()` differentiates these functions to ensure they won't be merged.
+extern fn voidret1() { dbg!() }
+extern fn voidret2() { dbg!() }
 
 extern fn uintret() -> usize { 22 }