drd: Avoid that an assertion failure is triggered if clone() fails.

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@12363 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/drd/drd_main.c b/drd/drd_main.c
index 364795e..3ac34df 100644
--- a/drd/drd_main.c
+++ b/drd/drd_main.c
@@ -639,7 +639,14 @@
 {
    DrdThreadId drd_tid;
 
+#if 0
+   /*
+    * The assert statement below doesn't hold if this function is invoked
+    * because thread creation failed. See e.g.
+    * coregrind/m_syswrap/syswrap-amd64-linux.c
+    */
    tl_assert(VG_(get_running_tid)() == vg_tid);
+#endif
 
    drd_tid = DRD_(VgThreadIdToDrdThreadId)(vg_tid);
    if (DRD_(thread_get_trace_fork_join)())