Add appropriate casts for char16_t.

C++11 defines a real char16_t, which is not implicitly convertible to
uint16_t (and by extension jchar). Add casts as needed.

Bug: 18300613
Change-Id: I00752002ef2e938bdb57f70947e8fd53ec103293
diff --git a/core/jni/android_os_Debug.cpp b/core/jni/android_os_Debug.cpp
index 92a9eee..db32272 100644
--- a/core/jni/android_os_Debug.cpp
+++ b/core/jni/android_os_Debug.cpp
@@ -896,7 +896,8 @@
     const jchar* str = env->GetStringCritical(fileName, 0);
     String8 fileName8;
     if (str) {
-        fileName8 = String8(str, env->GetStringLength(fileName));
+        fileName8 = String8(reinterpret_cast<const char16_t*>(str),
+                            env->GetStringLength(fileName));
         env->ReleaseStringCritical(fileName, str);
     }