Port flexible array members to GCC + valgrind

These changes are needed to conform to the C standard's rule for
allocating structs containing flexible array members.  C11 says
that malloc (offsetof (struct s, m) + n) does not suffice to
allocate a struct with an n-byte tail; instead, malloc’s arg
should be rounded up to the nearest multiple of alignof (struct s).
Although this is arguably a defect in C11, gcc -O2 + valgrind
sometimes complains when this rule is violated, and when debugging
it’s better to keep valgrind happy.
For details please see the thread containing the message at:
https://gcc.gnu.org/ml/gcc-patches/2016-09/msg00416.html
* lib-src/ebrowse.c, src/alloc.c, src/image.c, src/process.c:
Include flexmember.h.
* lib-src/ebrowse.c (add_sym, add_member, make_namespace)
(register_namespace_alias):
* src/alloc.c (SDATA_SIZE, allocate_string_data):
* src/image.c (xpm_cache_color, imagemagick_create_cache):
* src/process.c (Fmake_network_process):
Use FLEXSIZEOF instead of offsetof and addition.
* src/alloc.c (SDATA_SIZE, vector_alignment):
Use FLEXALIGNOF instead of sizeof (ptrdiff_t).
* src/lisp.h (ALIGNOF_STRUCT_LISP_VECTOR):
Remove, as alloc.c can now calculate this on its own.

1 files changed, 0 insertions, 7 deletions

diff --git a/src/lisp.h b/src/lisp.h
index 97c8d9fe84f..29ed9fe8a2d 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -1429,13 +1429,6 @@ struct Lisp_Vector
     Lisp_Object contents[FLEXIBLE_ARRAY_MEMBER];
   };
 
-/* C11 prohibits alignof (struct Lisp_Vector), so compute it manually.  */
-enum
-  {
-    ALIGNOF_STRUCT_LISP_VECTOR
-      = alignof (union { struct vectorlike_header a; Lisp_Object b; })
-  };
-
 /* A boolvector is a kind of vectorlike, with contents like a string.  */
 
 struct Lisp_Bool_Vector