6507 i386 makecontext(3c) needs to 16-byte align the stack

*** 27,44 ****
  #include <procfs.h>
  #include <ucontext.h>
  #include <setjmp.h>
  
  /*
!  * The i386 ABI says that the stack pointer need be only 4-byte aligned
!  * before a function call (STACK_ALIGN == 4).  We use a 16-byte stack
!  * alignment for the benefit of floating point code compiled using sse2.
!  * Even though the i386 ABI doesn't require it, both cc and gcc
!  * assume this alignment on entry to a function and maintain it
!  * for calls made from that function.  If the stack is initially
!  * aligned on a 16-byte boundary, it will continue to be so aligned.
!  * If it is not initially so aligned, it will never become so aligned.
   */
  #undef  STACK_ALIGN
  #define STACK_ALIGN     16
  
  extern int getlwpstatus(thread_t, lwpstatus_t *);
--- 27,45 ----
  #include <procfs.h>
  #include <ucontext.h>
  #include <setjmp.h>
  
  /*
!  * The stack needs to be 16-byte aligned with a 4-byte bias.  See comment in
!  * lib/libc/i386/gen/makectxt.c.
!  *
!  * Note: If you change it, you need to change it in the following files as
!  * well:
!  *
!  *  - lib/libc/i386/gen/makectxt.c
!  *  - lib/common/i386/crti.s
!  *  - lib/common/i386/crt1.s
   */
  #undef  STACK_ALIGN
  #define STACK_ALIGN     16
  
  extern int getlwpstatus(thread_t, lwpstatus_t *);