[PATCH hurd] Improve portability for rpctrace on x86_64

[Flavio Cruz]

Defined alignment as __alignof__(uintptr_t) to match MiG.

Also used char* instead of void* during the message iteration since it's
more portable as pointer arithmetic on void* is a GNU extension.
---
 utils/rpctrace.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/utils/rpctrace.c b/utils/rpctrace.c
index c2bc0062..09edc1e8 100644
--- a/utils/rpctrace.c
+++ b/utils/rpctrace.c
@@ -41,6 +41,9 @@
 
 #include "msgids.h"
 
+/* Should match MiG's desired_complex_alignof */
+#define MSG_ALIGNMENT __alignof__(uintptr_t)
+
 const char *argp_program_version = STANDARD_HURD_VERSION (rpctrace);
 
 static unsigned strsize = 80;
@@ -807,7 +810,7 @@ print_contents (mach_msg_header_t *inp,
   int first = 1;
 
   /* Process the message data, wrapping ports and printing data.  */
-  while (msg_buf_ptr < (void *) inp + inp->msgh_size)
+  while (msg_buf_ptr < (char *) inp + inp->msgh_size)
     {
       mach_msg_type_t *const type = msg_buf_ptr;
       mach_msg_type_long_t *const lt = (void *) type;
@@ -839,8 +842,7 @@ print_contents (mach_msg_header_t *inp,
          msg_buf_ptr += sizeof (void *);
        }
       else
-       msg_buf_ptr += ((nelt * eltsize + sizeof(natural_t) - 1)
-                       & ~(sizeof(natural_t) - 1));
+       msg_buf_ptr += ((nelt * eltsize + MSG_ALIGNMENT - 1) & ~(MSG_ALIGNMENT 
- 1));
 
       if (first)
        first = 0;
-- 
2.39.2