Added h files from SupportLib.

h/realloc

+/* Copyright 1996 Acorn Computers Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef realloc_H
+#define realloc_H
+
+/*realloc.c - portable realloc with no bugs!*/
+
+#include <stddef.h>
+
+extern void *REALLOC (void *ptr, size_t size);
+
+#endif