common: Fix iobuf API of filter function for alignment.

* common/iobuf.h (IOBUFCTRL_DESC): Change the call semantics.
* common/iobuf.c (iobuf_desc): Add the second argument DESC.
(print_chain, iobuf_close, do_open, iobuf_sockopen, iobuf_ioctl)
(iobuf_push_filter2, pop_filter, iobuf_write_temp): Change calls
of iobuf_desc.
(file_filter, file_es_filter, sock_filter, block_filter): Fill the
description.
* common/t-iobuf.c (every_other_filter, double_filter): Likewise.
* g10/armor.c, g10/cipher.c, g10/compress-bz2.c, g10/compress.c,
g10/decrypt-data.c, g10/encrypt.c, g10/mdfilter.c, g10/progress.c,
g10/textfilter.c: Likewise.

--

Newer GCC warns against possible alignment difference of pointers.
This change can silence those warnings.

Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>

common/iobuf.h

@@ -404,10 +404,10 @@ int iobuf_cancel (iobuf_t iobuf);
        called on the pipeline.
 
      IOBUFCTRL_DESC: Called with this value to get a human-readable
-       description of the filter.  * (char **) BUF should set to the
-       NUL-terminated string.  Note: you need to keep track of this
-       value and, if necessary, free it when the filter function is
-       called with control set to IOBUFCTRL_FREE.
+       description of the filter.  *LEN is the size of the buffer.
+       The description is filled into BUF, NUL-terminated.  Always
+       returns 0.  When the size of the buffer is shorter than the
+       description, it is truncated and not NUL-terminated.
   */
 int iobuf_push_filter (iobuf_t a, int (*f) (void *opaque, int control,
 					    iobuf_t chain, byte * buf,