Revert "[CodeGen] Fix invalid DWARF info on Win64"

Appears to break on build bots. Reverting pending investigation.

llvm-svn: 289014
diff --git a/llvm/docs/Extensions.rst b/llvm/docs/Extensions.rst
index 850c427..6c50abf 100644
--- a/llvm/docs/Extensions.rst
+++ b/llvm/docs/Extensions.rst
@@ -67,7 +67,7 @@
     .long 4
     .long 242
     .long 40
-    .secrel32 _function_name + 0
+    .secrel32 _function_name
     .secidx   _function_name
     ...