CERES_DONT_HAVE_PROTOCOL_BUFFERS -> CERES_NO_PROTOCOL_BUFFERS.

Change-Id: I6c9f50e4c006faf4e75a8f417455db18357f3187
diff --git a/internal/ceres/matrix_proto.h b/internal/ceres/matrix_proto.h
index b8a3a1a..94b3076 100644
--- a/internal/ceres/matrix_proto.h
+++ b/internal/ceres/matrix_proto.h
@@ -33,7 +33,7 @@
 #ifndef CERES_INTERNAL_MATRIX_PROTO_H_
 #define CERES_INTERNAL_MATRIX_PROTO_H_
 
-#ifndef CERES_DONT_HAVE_PROTOCOL_BUFFERS
+#ifndef CERES_NO_PROTOCOL_BUFFERS
 #include "ceres/matrix.pb.h"
 #endif