dbghelp: Fix stabs_pts_read_type_def() for when typename is NULL

[Andrew Talbot]

Changelog:
    dbghelp: Fix stabs_pts_read_type_def() for when typename is NULL.

diff --git a/dlls/dbghelp/stabs.c b/dlls/dbghelp/stabs.c
index d550633..3c69eec 100644
--- a/dlls/dbghelp/stabs.c
+++ b/dlls/dbghelp/stabs.c
@@ -896,10 +896,10 @@ static int stabs_pts_read_type_def(struct ParseTypedefData* ptd, const char* typ
                      * removed
                      */
                     l1 = strlen(udt->hash_elt.name);
-                    l2 = strlen(typename);
-                    if (l1 > l2 || strcmp(udt->hash_elt.name, typename + l2 - l1))
+                    l2 = typename ? strlen(typename) : 0;
+                    if (l1 > l2 || (typename && strcmp(udt->hash_elt.name, typename + l2 - l1)))
                         ERR("Forward declaration name mismatch %s <> %s\n",
-                            udt->hash_elt.name, typename);
+                            udt->hash_elt.name, typename ? typename : "(null)");
                     new_dt = &udt->symt;
                 }
                 PTS_ABORTIF(ptd, stabs_pts_read_aggregate(ptd, udt) == -1);
@@ -1003,7 +1003,7 @@ static int stabs_pts_read_type_def(struct ParseTypedefData* ptd, const char* typ
 
     *stabs_find_ref(filenr1, subnr1) = *ret_dt = new_dt;
 
-    TRACE("Adding (%ld,%ld) %s\n", filenr1, subnr1, typename);
+    TRACE("Adding (%ld,%ld) %s\n", filenr1, subnr1, typename ? typename : "(null)");
 
     return 0;
 }