[LyX/master] fix distcheck

[Pavel Sanda]

commit 59e84a525fe70f28e3c0f8887f9d779e641d28ed
Author: Pavel Sanda <sanda at lyx.org>
Date:   Fri Apr 10 14:28:59 2020 +0200

    fix distcheck
---
 3rdparty/Makefile.am |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/3rdparty/Makefile.am b/3rdparty/Makefile.am
index bcc195b..e21e1cb 100644
--- a/3rdparty/Makefile.am
+++ b/3rdparty/Makefile.am
@@ -1,6 +1,6 @@
 include $(top_srcdir)/config/common.am
 
-DIST_SUBDIRS = boost hunspell mythes libiconv zlib
+DIST_SUBDIRS = boost dtl hunspell mythes libiconv zlib
 
 if USE_INCLUDED_BOOST
 if LYX_USE_STD_REGEX