Avoid crashing on non-initialized debug info.

diff --git a/dlls/ntdll/debugtools.c b/dlls/ntdll/debugtools.c
index d91cec2..8354bef 100644
--- a/dlls/ntdll/debugtools.c
+++ b/dlls/ntdll/debugtools.c
@@ -170,7 +170,7 @@
 const char *wine_dbgstr_an( const char *src, int n )
 {
     char *res, *old_pos;
-    struct debug_info *info;
+    struct debug_info *info = get_info();
 
     if (!HIWORD(src))
     {
@@ -180,7 +180,6 @@
         return res;
     }
     /* save current position to restore it on exception */
-    info = NtCurrentTeb()->debug_info;
     old_pos = info->str_pos;
     __TRY
     {
@@ -201,7 +200,7 @@
 const char *wine_dbgstr_wn( const WCHAR *src, int n )
 {
     char *res, *old_pos;
-    struct debug_info *info;
+    struct debug_info *info = get_info();
 
     if (!HIWORD(src))
     {
@@ -212,7 +211,6 @@
     }
 
     /* save current position to restore it on exception */
-    info = NtCurrentTeb()->debug_info;
     old_pos = info->str_pos;
     __TRY
     {