Switch NULL to C++11 nullptr in source/Interpreter

Patch by Robert Matusewicz

llvm-svn: 206711
diff --git a/lldb/source/Interpreter/OptionValueUUID.cpp b/lldb/source/Interpreter/OptionValueUUID.cpp
index 340f1e5..0141911 100644
--- a/lldb/source/Interpreter/OptionValueUUID.cpp
+++ b/lldb/source/Interpreter/OptionValueUUID.cpp
@@ -92,7 +92,7 @@
         if (num_modules > 0)
         {
             UUID::ValueType uuid_bytes;
-            const size_t num_bytes_decoded = UUID::DecodeUUIDBytesFromCString(s, uuid_bytes, NULL);
+            const size_t num_bytes_decoded = UUID::DecodeUUIDBytesFromCString(s, uuid_bytes, nullptr);
             for (size_t i=0; i<num_modules; ++i)
             {
                 ModuleSP module_sp (target->GetImages().GetModuleAtIndex(i));