Add missing <malloc.h> and <string.h> includes.

Change-Id: Ia41756e607663d056e7d2fdd7ecbec7e5841a913
diff --git a/libmemtrack/memtrack.c b/libmemtrack/memtrack.c
index 5d68083..21d9ebd 100644
--- a/libmemtrack/memtrack.c
+++ b/libmemtrack/memtrack.c
@@ -21,6 +21,9 @@
 #include <log/log.h>
 
 #include <errno.h>
+#include <malloc.h>
+#include <string.h>
+
 #include <hardware/memtrack.h>
 
 #define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))