Update to a more recent LLVM. (#7488)

Fix a few API issues. There's also a newly-added file in compiler-rt
that is not supposed to be built by default but is not being excluded
properly by a glob. Added a patch to exclude that and sent
https://github.com/llvm/llvm-project/pull/208861 upstream.

toolchain/check/cpp/call.cpp

@@ -310,7 +310,7 @@ static auto BuildTemplateId(Context& context, SemIR::LocId loc_id,
           dyn_cast<clang::VarTemplateDecl>(template_decl)) {
     auto decl_result = context.clang_sema().CheckVarTemplateId(
         var_template_decl, /*TemplateLoc=*/clang::SourceLocation(), loc,
-        arg_list, /*SetWrittenArgs=*/false);
+        arg_list);
     return decl_result.isInvalid()
                ? SemIR::ErrorInst::InstId
                : ImportCppDecl(context, loc_id,