Update notes for submitted changes

* Avoid redefinition of __STDC_CONSTANT_MACROS.
Update notes for submitted changes

* Make LLVM build on AArch64.
Update notes for submitted changes

* Enable x86_64 build
Update notes for submitted changes

* Make LLVM compile with prebuilt clang.
Update notes for submitted changes

* Revert "Make LLVM compile with prebuilt clang."