Fix google-explicit-constructor warnings in art.

* Add explicit keyword to conversion constructors,
  or NOLINT for implicit converters.
Bug: 28341362
Test: build with WITH_TIDY=1

Change-Id: I1e1ee2661812944904fedadeff97b620506db47d
diff --git a/compiler/optimizing/locations.h b/compiler/optimizing/locations.h
index 4384042..c97c4a6 100644
--- a/compiler/optimizing/locations.h
+++ b/compiler/optimizing/locations.h
@@ -488,9 +488,9 @@
     kCallOnMainOnly
   };
 
-  LocationSummary(HInstruction* instruction,
-                  CallKind call_kind = kNoCall,
-                  bool intrinsified = false);
+  explicit LocationSummary(HInstruction* instruction,
+                           CallKind call_kind = kNoCall,
+                           bool intrinsified = false);
 
   void SetInAt(uint32_t at, Location location) {
     inputs_[at] = location;