tracing: Move buffer in trace_seq to end of struct

TRACE_SEQ_BUFFER_SIZE is dependent on the architecture for its size. on 64-bit
systems, it is 8148 bytes. forced 8-byte alignment in size_t and seq_buf means
that trace_seq is 8200 bytes on 64-bit systems. moving the buffer to the end
of the struct fixes the issue. there shouldn't be any side effects, i.e.
pointer arithmetic on trace_seq

Cc: Masami Hiramatsu <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Link: https://lore.kernel.org/[email protected]
Signed-off-by: Elijah Wright <[email protected]>
Signed-off-by: Steven Rostedt (Google) <[email protected]>

Author: elijah-wright

include/linux/trace_seq.h

@@ -21,10 +21,10 @@
 	(sizeof(struct seq_buf) + sizeof(size_t) + sizeof(int)))
 
 struct trace_seq {
-	char			buffer[TRACE_SEQ_BUFFER_SIZE];
 	struct seq_buf		seq;
 	size_t			readpos;
 	int			full;
+	char                    buffer[TRACE_SEQ_BUFFER_SIZE];
 };
 
 static inline void