frameworks/native: Fix build in ISO C++11 mode

Change-Id: Icc19cde1bf9c72397ed8bda545e9056483d83e8d
Signed-off-by: Bernhard Rosenkraenzer <Bernhard.Rosenkranzer@linaro.org>
diff --git a/include/utils/Unicode.h b/include/utils/Unicode.h
index 9273533..443f66d 100644
--- a/include/utils/Unicode.h
+++ b/include/utils/Unicode.h
@@ -22,8 +22,10 @@
 
 extern "C" {
 
+#if __cplusplus < 201103L && !defined(__GXX_EXPERIMENTAL_CXX0X__) && !defined(char16_t)
 typedef uint32_t char32_t;
 typedef uint16_t char16_t;
+#endif
 
 // Standard string functions on char16_t strings.
 int strcmp16(const char16_t *, const char16_t *);