ntdll: Use #ifdef to check for potentially undefined macros.

[Francois Gouget]

---

autoconf macros are either undefined or 1 so #ifdef feels more correct.

 dlls/ntdll/signal_x86_64.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/dlls/ntdll/signal_x86_64.c b/dlls/ntdll/signal_x86_64.c
index 9b98894..575a770 100644
--- a/dlls/ntdll/signal_x86_64.c
+++ b/dlls/ntdll/signal_x86_64.c
@@ -1431,7 +1431,7 @@ static NTSTATUS dwarf_virtual_unwind( ULONG64 ip, ULONG64 *frame,CONTEXT *contex
 }
 
 
-#if HAVE_LIBUNWIND_H
+#ifdef HAVE_LIBUNWIND_H
 /***********************************************************************
  *           libunwind_set_cursor_from_context
  */
@@ -2341,7 +2341,7 @@ static NTSTATUS call_stack_handlers( EXCEPTION_RECORD *rec, CONTEXT *orig_contex
                 if (status != STATUS_SUCCESS) return status;
                 got_info = TRUE;
             }
-#if HAVE_LIBUNWIND_H
+#ifdef HAVE_LIBUNWIND_H
             else
             {
                 status = libunwind_virtual_unwind( context.Rip, &got_info, &dispatch.EstablisherFrame, &new_context,
@@ -3369,7 +3369,7 @@ void WINAPI RtlUnwindEx( PVOID end_frame, PVOID target_ip, EXCEPTION_RECORD *rec
                 if (status != STATUS_SUCCESS) raise_status( status, rec );
                 got_info = TRUE;
             }
-#if HAVE_LIBUNWIND_H
+#ifdef HAVE_LIBUNWIND_H
             else
             {
                 status = libunwind_virtual_unwind( context->Rip, &got_info, &dispatch.EstablisherFrame, &new_context,
-- 
2.4.6