Qualify use of llvm::empty that's ambiguous with std::empty

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@361968 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/MachineModuleInfo.cpp

@@ -209,7 +209,7 @@ bool MachineModuleInfo::doInitialization(Module &M) {
   HasSplitStack = HasNosplitStack = false;
   AddrLabelSymbols = nullptr;
   TheModule = &M;
-  DbgInfoAvailable = !empty(M.debug_compile_units());
+  DbgInfoAvailable = !llvm::empty(M.debug_compile_units());
   return false;
 }