[libglnx] build-sys: Fix make dist

[Colin Walters <walters src gnome org>]

commit e5856ca2939dca0589a836e3108dd3f9759e28fa
Author: Colin Walters <walters verbum org>
Date:   Sun Sep 17 09:04:56 2017 -0400

    build-sys: Fix make dist
    
    The libostree Travis builds use make dist.

 Makefile-libglnx.am |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/Makefile-libglnx.am b/Makefile-libglnx.am
index 6df05ea..de6e49b 100644
--- a/Makefile-libglnx.am
+++ b/Makefile-libglnx.am
@@ -46,6 +46,7 @@ libglnx_la_SOURCES = \
        $(libglnx_srcpath)/glnx-shutil.h \
        $(libglnx_srcpath)/glnx-shutil.c \
        $(libglnx_srcpath)/libglnx.h \
+       $(libglnx_srcpath)/tests/libglnx-testlib.h \
        $(NULL)
 
 libglnx_la_CFLAGS = $(AM_CFLAGS) $(libglnx_cflags)