Fix google-explicit-constructor warnings.

Bug: 28341362
Change-Id: I0ce850de85e0de6a5472dd142f738856142db9ec
diff --git a/Static.cpp b/Static.cpp
index cd9509f..f0613d1 100644
--- a/Static.cpp
+++ b/Static.cpp
@@ -48,7 +48,7 @@
 class FdTextOutput : public BufferedTextOutput
 {
 public:
-    FdTextOutput(int fd) : BufferedTextOutput(MULTITHREADED), mFD(fd) { }
+    explicit FdTextOutput(int fd) : BufferedTextOutput(MULTITHREADED), mFD(fd) { }
     virtual ~FdTextOutput() { };
 
 protected: