[subset] Add some helper functions for writing tests around subsetting.
diff --git a/test/api/Makefile.am b/test/api/Makefile.am
index 9cda5ef..8c1c475 100644
--- a/test/api/Makefile.am
+++ b/test/api/Makefile.am
@@ -16,7 +16,7 @@
AM_CPPFLAGS = -DSRCDIR="\"$(srcdir)\"" -I$(top_srcdir)/src/ -I$(top_builddir)/src/ $(GLIB_CFLAGS)
LDADD = $(top_builddir)/src/libharfbuzz.la $(GLIB_LIBS)
-EXTRA_DIST += hb-test.h
+EXTRA_DIST += hb-test.h hb-subset-test.h
check_PROGRAMS = $(TEST_PROGS)
noinst_PROGRAMS = $(TEST_PROGS)