Fix missing std::. Not sure how this compiles for anyone else.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@177620 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/DebugInfo/DWARFDebugAranges.cpp b/lib/DebugInfo/DWARFDebugAranges.cpp
index b077eb5..f79862d 100644
--- a/lib/DebugInfo/DWARFDebugAranges.cpp
+++ b/lib/DebugInfo/DWARFDebugAranges.cpp
@@ -186,7 +186,7 @@
     Range range(address);
     RangeCollIterator begin = Aranges.begin();
     RangeCollIterator end = Aranges.end();
-    RangeCollIterator pos = lower_bound(begin, end, range, RangeLessThan);
+    RangeCollIterator pos = std::lower_bound(begin, end, range, RangeLessThan);
 
     if (pos != end && pos->LoPC <= address && address < pos->HiPC()) {
       return pos->Offset;