Use char16_t for char things.

When compiling in C++ mode, the compiler will complain about conversions
from uint16_t to char16_t. Be consistent in using char16_t for strings.

Change-Id: I052b6176ced635162920b31560052d9a64f92764
diff --git a/tools/aapt/StringPool.h b/tools/aapt/StringPool.h
index 1b3abfd..1b5a7ba 100644
--- a/tools/aapt/StringPool.h
+++ b/tools/aapt/StringPool.h
@@ -26,7 +26,7 @@
 
 #define PRINT_STRING_METRICS 0
 
-void strcpy16_htod(uint16_t* dst, const uint16_t* src);
+void strcpy16_htod(char16_t* dst, const char16_t* src);
 
 void printStringPool(const ResStringPool* pool);