ntdll: Make sure the stack is quad-word aligned on ARM64 (try 2)

[André Hentschel]

EXCEPTION_RECORD is not correctly aligned and until bd1f7ef1868dd563a82eacd1bf414bf8d1a7254e, CONTEXT wasn't either,
which ended in an correctly aligned structure, but the mentioned commit changed that.

Signed-off-by: André Hentschel <nerv at dawncrow.de>
---
 dlls/ntdll/signal_arm64.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/dlls/ntdll/signal_arm64.c b/dlls/ntdll/signal_arm64.c
index 3a51567..1baf5a8 100644
--- a/dlls/ntdll/signal_arm64.c
+++ b/dlls/ntdll/signal_arm64.c
@@ -386,8 +386,8 @@ static EXCEPTION_RECORD *setup_exception( ucontext_t *sigcontext, raise_func fun
     } *stack;
     DWORD exception_code = 0;
 
-    stack = (struct stack_layout *)(SP_sig(sigcontext) & ~15);
-    stack--;  /* push the stack_layout structure */
+    /* push the stack_layout structure */
+    stack = (struct stack_layout *)((SP_sig(sigcontext) - sizeof(stack[0])) & ~15);
 
     stack->rec.ExceptionRecord  = NULL;
     stack->rec.ExceptionCode    = exception_code;
-- 
2.7.4