Replace all occurences of exit() in potential library code

by appropriate return values.


git-svn-id: svn://svn.savannah.nongnu.org/avrdude/trunk/avrdude@1301 81a1dc3b-b13d-400b-aceb-764788c761c2

flip2.c

@@ -830,7 +830,7 @@ int flip2_write_max1k(struct dfu_dev *dfu,
   if (size > 0x400) {
     fprintf(stderr, "%s: Error: Write block too large (%hu > 1024)\n",
       progname, size);
-    exit(1);
+    return -1;
   }
 
   /* There are some special padding requirements for writes. The first packet