rb_{thread,context,fiber}_struct: trivial packing

* vm_core.h (rb_thread_struct): reorder to pack
* cont.c (rb_context_struct, rb_fiber_struct): ditto
  On x86-64, these changes reduces:
  rb_thread_struct to 1000 bytes (from 1016)
  rb_context_struct to 1288 bytes (from 1312)
  rb_fiber_struct to 2272 bytes (from 2304)

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47186 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,12 @@
+Fri Aug 15 09:22:12 2014  Eric Wong  <e@80x24.org>
+
+	* vm_core.h (rb_thread_struct): reorder to pack
+	* cont.c (rb_context_struct, rb_fiber_struct): ditto
+	  On x86-64, these changes reduces:
+	  rb_thread_struct to 1000 bytes (from 1016)
+	  rb_context_struct to 1288 bytes (from 1312)
+	  rb_fiber_struct to 2272 bytes (from 2304)
+
 Fri Aug 15 09:06:31 2014  Eric Wong  <e@80x24.org>
 
 	* thread_pthread.h: define RB_NATIVETHREAD_LOCK_INIT and

cont.c

@@ -89,8 +89,8 @@ enum context_type {
 
 typedef struct rb_context_struct {
     enum context_type type;
-    VALUE self;
     int argc;
+    VALUE self;
     VALUE value;
     VALUE *vm_stack;
 #ifdef CAPTURE_JUST_VALID_VM_STACK
@@ -134,14 +134,14 @@ typedef struct rb_fiber_struct {
     rb_context_t cont;
     VALUE prev;
     enum fiber_status status;
-    struct rb_fiber_struct *prev_fiber;
-    struct rb_fiber_struct *next_fiber;
     /* If a fiber invokes "transfer",
      * then this fiber can't "resume" any more after that.
      * You shouldn't mix "transfer" and "resume".
      */
     int transfered;
 
+    struct rb_fiber_struct *prev_fiber;
+    struct rb_fiber_struct *next_fiber;
 #if FIBER_USE_NATIVE
 #ifdef _WIN32
     void *fib_handle;

vm_core.h

@@ -599,6 +599,7 @@ typedef struct rb_thread_struct {
     enum rb_thread_status status;
     int to_kill;
     int priority;
+    int mark_stack_len;
 
     native_thread_data_t native_thread_data;
     void *blocking_region_buffer;
@@ -616,8 +617,8 @@ typedef struct rb_thread_struct {
 
     /* async errinfo queue */
     VALUE pending_interrupt_queue;
-    int pending_interrupt_queue_checked;
     VALUE pending_interrupt_mask_stack;
+    int pending_interrupt_queue_checked;
 
     rb_atomic_t interrupt_flag;
     unsigned long interrupt_mask;
@@ -665,7 +666,6 @@ typedef struct rb_thread_struct {
 #endif
 	jmp_buf regs;
     } machine;
-    int mark_stack_len;
 
     /* statistics data for profiler */
     VALUE stat_insn_usage;