Update llvm/clang/lld to the latest version

This version allows clang to use address sanitizer for mingw,
adds support for linking against import libraries from GNU tools
and makes the linker provide the __CTOR_LIST__ symbol for better
compatibility with binutils based sysroots, and adds support for
thunks for armv7 (allowing linking armv7 binaries over 16 MB).

README.md

@@ -66,7 +66,6 @@ Known issues
 LLD, the LLVM linker, is what causes most of the major differences to the
 normal GCC/binutils based MinGW.
 
-- LLD doesn't support using import libraries created by GNU tools.
 - The windres replacement, llvm-rc, isn't very mature and doesn't support
   everything that GNU windres does.
 - The DLL version of libc++ doesn't have a fixed supported ABI, so in theory,