Rename _LIBCPP_DEBUG2 to _LIBCPP_DEBUG.

llvm-svn: 189140
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 145afa17caedb3ff6d58dfd75dd72047810190d1
diff --git a/src/debug.cpp b/src/debug.cpp
index e840b22..d0e8679 100644
--- a/src/debug.cpp
+++ b/src/debug.cpp
@@ -7,7 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#define _LIBCPP_DEBUG2 1
+#define _LIBCPP_DEBUG 1
 #include "__config"
 #include "__debug"
 #include "functional"