Unify NDK platform headers.

This commit removes duplication of system headers per platform, i.e. remove
copies of common headers like <stdlib.h> from arch-arm/usr/include and arch-x86/usr/include
and move them to a common include directory. More specifically:

- common headers:        android-N/arch-A/usr/include --> android-N/include
- arch-specific headers: android-N/arch-A/usr-include --> android-N/arch-A/include
- arch-specific libs:    android-N/arch-A/usr/lib     --> android-N/arch-A/lib

Change-Id: Ifdba5038d108901931f3e3a7c14ebe6270d2d276

NOTE: This also contains careful separation of API-level-specific headers.
      For example, platforms/android-5/include/pthread.h contains new function
      declarations that are not available when using platforms/android-3/include/pthread.h

NOTE: The NDK's build-platforms.sh script has been updated to understand the new
      layout. This change in develeopment/ndk does not change the layout of
      platform files under $NDK/platforms after build-platforms.sh is called.

ndk/platforms/android-3/arch-arm/include/asm/unaligned.h

@@ -0,0 +1,38 @@
+/****************************************************************************
+ ****************************************************************************
+ ***
+ ***   This header was automatically generated from a Linux kernel header
+ ***   of the same name, to make information necessary for userspace to
+ ***   call into the kernel available to libc.  It contains only constants,
+ ***   structures, and macros generated from the original header, and thus,
+ ***   contains no copyrightable information.
+ ***
+ ****************************************************************************
+ ****************************************************************************/
+#ifndef __ASM_ARM_UNALIGNED_H
+#define __ASM_ARM_UNALIGNED_H
+
+#include <asm/types.h>
+
+#define __get_unaligned_2_le(__p)   (__p[0] | __p[1] << 8)
+
+#define __get_unaligned_2_be(__p)   (__p[0] << 8 | __p[1])
+
+#define __get_unaligned_4_le(__p)   (__p[0] | __p[1] << 8 | __p[2] << 16 | __p[3] << 24)
+
+#define __get_unaligned_4_be(__p)   (__p[0] << 24 | __p[1] << 16 | __p[2] << 8 | __p[3])
+
+#define __get_unaligned_le(ptr)   ({   __typeof__(*(ptr)) __v;   __u8 *__p = (__u8 *)(ptr);   switch (sizeof(*(ptr))) {   case 1: __v = *(ptr); break;   case 2: __v = __get_unaligned_2_le(__p); break;   case 4: __v = __get_unaligned_4_le(__p); break;   case 8: {   unsigned int __v1, __v2;   __v2 = __get_unaligned_4_le((__p+4));   __v1 = __get_unaligned_4_le(__p);   __v = ((unsigned long long)__v2 << 32 | __v1);   }   break;   default: __v = __bug_unaligned_x(__p); break;   }   __v;   })
+
+#define __get_unaligned_be(ptr)   ({   __typeof__(*(ptr)) __v;   __u8 *__p = (__u8 *)(ptr);   switch (sizeof(*(ptr))) {   case 1: __v = *(ptr); break;   case 2: __v = __get_unaligned_2_be(__p); break;   case 4: __v = __get_unaligned_4_be(__p); break;   case 8: {   unsigned int __v1, __v2;   __v2 = __get_unaligned_4_be(__p);   __v1 = __get_unaligned_4_be((__p+4));   __v = ((unsigned long long)__v2 << 32 | __v1);   }   break;   default: __v = __bug_unaligned_x(__p); break;   }   __v;   })
+
+#define __put_unaligned_le(val,ptr)   ({   switch (sizeof(*(ptr))) {   case 1:   *(ptr) = (val);   break;   case 2: __put_unaligned_2_le((val),(__u8 *)(ptr));   break;   case 4: __put_unaligned_4_le((val),(__u8 *)(ptr));   break;   case 8: __put_unaligned_8_le((val),(__u8 *)(ptr));   break;   default: __bug_unaligned_x(ptr);   break;   }   (void) 0;   })
+#define __put_unaligned_be(val,ptr)   ({   switch (sizeof(*(ptr))) {   case 1:   *(ptr) = (val);   break;   case 2: __put_unaligned_2_be((val),(__u8 *)(ptr));   break;   case 4: __put_unaligned_4_be((val),(__u8 *)(ptr));   break;   case 8: __put_unaligned_8_be((val),(__u8 *)(ptr));   break;   default: __bug_unaligned_x(ptr);   break;   }   (void) 0;   })
+#ifndef __ARMEB__
+#define get_unaligned __get_unaligned_le
+#define put_unaligned __put_unaligned_le
+#else
+#define get_unaligned __get_unaligned_be
+#define put_unaligned __put_unaligned_be
+#endif
+#endif