Fix some implicit declaration warnings.

git-svn-id: svn://svn.savannah.nongnu.org/avrdude/trunk/avrdude@183 81a1dc3b-b13d-400b-aceb-764788c761c2

pgm.c

@@ -19,8 +19,9 @@
 
 /* $Id$ */
 
-#include <stdlib.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include "pgm.h"
 

ppi.c

@@ -20,6 +20,7 @@
 /* $Id$ */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <fcntl.h>
 #include <unistd.h>

stk500.c

@@ -29,6 +29,7 @@
  */
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <fcntl.h>
 #include <unistd.h>