Fix issues that will be present in C++11

- char16_t is a distinct type, so stay consistent
  with it throughout the code base.
- char16_t is defined as minimum size of 16 bits.
  Since we mmap and cast data structures onto raw memory,
  we need a precise definition (uint16_t), so we cast between
  that (and static_assert that they are the same size).

Change-Id: I869c32637543bbcfb39d2643e7d9df10d33acd3c
diff --git a/tools/aapt/Main.cpp b/tools/aapt/Main.cpp
index 2857b59..18b8e1e 100644
--- a/tools/aapt/Main.cpp
+++ b/tools/aapt/Main.cpp
@@ -11,9 +11,9 @@
 #include <utils/List.h>
 #include <utils/Errors.h>
 
-#include <stdlib.h>
+#include <cstdlib>
 #include <getopt.h>
-#include <assert.h>
+#include <cassert>
 
 using namespace android;