[ASan] Move GetCurrentThread/SetCurrentThread from AsanThreadRegistry class into plain functions: they don't actually use registry

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@177501 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/asan/asan_linux.cc b/lib/asan/asan_linux.cc
index b2df5a9..58b96a6 100644
--- a/lib/asan/asan_linux.cc
+++ b/lib/asan/asan_linux.cc
@@ -116,7 +116,7 @@
   if (max_s > 1) {
     stack->max_size = max_s;
     if (!asan_inited) return;
-    if (AsanThread *t = asanThreadRegistry().GetCurrent())
+    if (AsanThread *t = GetCurrentThread())
       stack->FastUnwindStack(pc, bp, t->stack_top(), t->stack_bottom());
   }
 }