clean up includes and remove non-portable includes

This marginally increases the portability of hardened_malloc,
eg. on OSX.

test/impossibly_large_malloc.c

@@ -1,5 +1,4 @@
-#include <malloc.h>
-#include <stddef.h>
+#include <stdlib.h>
 
 #include "test_util.h"
 

test/invalid_malloc_object_size_small.c

@@ -1,4 +1,4 @@
-#include <malloc.h>
+#include <stdlib.h>
 
 #include "test_util.h"
 

test/invalid_malloc_object_size_small_quarantine.c

@@ -1,4 +1,4 @@
-#include <malloc.h>
+#include <stdlib.h>
 
 #include "test_util.h"
 

test/mallinfo.c

@@ -1,6 +1,9 @@
+#include <stdlib.h>
 #include <stdio.h>
 
+#if defined(__GLIBC__) || defined(__ANDROID__)
 #include <malloc.h>
+#endif
 
 #include "test_util.h"
 

test/mallinfo2.c

@@ -1,6 +1,9 @@
 #include <stdio.h>
+#include <stdlib.h>
 
+#if defined(__GLIBC__)
 #include <malloc.h>
+#endif
 
 #include "test_util.h"
 

test/malloc_info.c

@@ -1,7 +1,9 @@
 #include <pthread.h>
 #include <stdio.h>
 
+#if defined(__GLIBC__) || defined(__ANDROID__)
 #include <malloc.h>
+#endif
 
 #include "test_util.h"
 #include "../util.h"

test/malloc_object_size.c

@@ -1,5 +1,5 @@
 #include <stdbool.h>
-#include <malloc.h>
+#include <stdlib.h>
 
 #include "test_util.h"
 

test/malloc_object_size_offset.c

@@ -1,5 +1,5 @@
 #include <stdbool.h>
-#include <malloc.h>
+#include <stdlib.h>
 
 #include "test_util.h"
 

test/write_after_free_large.c

@@ -1,5 +1,4 @@
 #include <stdlib.h>
-#include <string.h>
 
 #include "test_util.h"
 

test/write_after_free_small.c

@@ -1,5 +1,4 @@
 #include <stdlib.h>
-#include <string.h>
 
 #include "test_util.h"
 

test/write_after_free_small_reuse.c

@@ -1,5 +1,4 @@
 #include <stdlib.h>
-#include <string.h>
 
 #include "test_util.h"
 #include "../util.h"

test/write_zero_size.c

@@ -1,5 +1,4 @@
 #include <stdlib.h>
-#include <stdio.h>
 
 #include "test_util.h"