[LyX/master] fix merged build

[Peter Kümmel]

commit 936ec661247e0997fbedbb9a6bab5ba7e19f2715
Author: Peter Kümmel <kuem...@lyx.org>
Date:   Wed Jan 6 12:55:12 2016 +0100

    fix merged build

diff --git a/src/TextClass.h b/src/TextClass.h
index 94fe003..a6ffed9 100644
--- a/src/TextClass.h
+++ b/src/TextClass.h
@@ -30,6 +30,10 @@
 #include <string>
 #include <vector>
 
+#ifdef ERROR
+#undef ERROR
+#endif
+
 namespace lyx {
 
 namespace support { class FileName; }