https://gitlab.com/jas/libidn2/issues/6

the release ships with this source file, so don't regen it on every build.
doing so breaks cross-compilation currently.

--- a/Makefile.am
+++ b/Makefile.am
@@ -66,7 +66,8 @@
 noinst_PROGRAMS = gentr46map
 gentr46map_LDADD = $(LTLIBUNISTRING)
 
-tr46map_data.c: gentr46map.c gentr46map$(EXEEXT) $(TR46MAP) $(NFCQC)
+tr46map_data.c: $(srcdir)/gentr46map.c $(TR46MAP) $(NFCQC)
+	$(MAKE) gentr46map$(EXEEXT)
 	$(builddir)/gentr46map$(EXEEXT) > $@.new
 	mv $@.new $@
 
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -34,7 +34,7 @@
 dist_man_MANS = idn2.1 $(gdoc_MANS)
 CLEANFILES = $(dist_man_MANS) lookup.c register.c stamp-vti version.texi $(srcdir)/libidn2.info
 
-idn2.1: $(top_srcdir)/src/idn2.c $(top_srcdir)/src/idn2.ggo $(top_srcdir)/configure.ac
+idn2.1: $(top_srcdir)/src/idn2.c $(top_srcdir)/src/idn2.ggo
 	$(HELP2MAN) \
 		--name="Libidn2 Internationalized Domain Names (IDNA2008/TR46) conversion" \
 		--output=$@ \