Fix headers to be included alone

Change-Id: I7eb9a6ed51b938506d440b91e6b3d42daf817fd7

ndk/platforms/android-21/include/GLES2/gl2ext.h

@@ -1,6 +1,8 @@
 #ifndef __gl2ext_h_
 #define __gl2ext_h_ 1
 
+#include <GLES2/gl2.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif

ndk/platforms/android-21/include/android/dlext.h

@@ -19,6 +19,7 @@
 
 #include <stddef.h>
 #include <sys/cdefs.h>
+#include <stdint.h>
 
 __BEGIN_DECLS
 

ndk/platforms/android-21/include/fts.h

@@ -35,6 +35,8 @@
 #ifndef	_FTS_H_
 #define	_FTS_H_
 
+#include <sys/types.h>
+
 typedef struct {
 	struct _ftsent *fts_cur;	/* current node */
 	struct _ftsent *fts_child;	/* linked list of children */

ndk/platforms/android-21/include/sgidefs.h

@@ -29,6 +29,8 @@
 #ifndef _SGIDEFS_H_
 #define _SGIDEFS_H_
 
+#ifdef __mips__
 #include <asm/sgidefs.h>
+#endif
 
 #endif /* _SGIDEFS_H_ */

ndk/platforms/android-21/include/sys/user.h

@@ -31,6 +31,7 @@
 
 #include <sys/cdefs.h>
 #include <limits.h> /* For PAGE_SIZE. */
+#include <stddef.h> /* For size_t */
 
 __BEGIN_DECLS
 

ndk/platforms/android-3/include/sys/user.h

@@ -31,6 +31,7 @@
 
 #include <sys/cdefs.h>
 #include <limits.h> /* For PAGE_SIZE. */
+#include <stddef.h> /* For size_t */
 
 __BEGIN_DECLS