Eliminate use of malloc.h.

epplets/mbox.c

@@ -21,6 +21,7 @@
    the above people for their excellent work. -- mej */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 #include <sys/types.h>
@@ -32,7 +33,6 @@
 #include <string.h>
 #include <time.h>
 #include <utime.h>
-#include <malloc.h>
 #include <limits.h>
 
 #define ISSPACE(c) isspace((unsigned char) c)