steps towards making 'make distcheck' work

'make distcheck' checks for out-of-source-tree builds and whether
the distribution tarball includes all source files.  This commit
fixes many problems, except some remaining with src/test still
to-be-fixd.
diff --git a/Makefile.am b/Makefile.am
index af437a6..13cec6c 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1 +1,3 @@
 SUBDIRS = src
+
+EXTRA_DIST = asn1
diff --git a/src/Makefile.am b/src/Makefile.am
index 9e0f59d..0a54e01 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -37,7 +37,8 @@
 noinst_HEADERS = hnbap_common.h hnbap_ies_defs.h \
 		 rua_common.h rua_ies_defs.h \
 		 context_map.h hnbgw.h hnbgw_cn.h \
-		 hnbgw_hnbap.h hnbgw_rua.h hnbgw_ranap.h
+		 hnbgw_hnbap.h hnbgw_rua.h hnbgw_ranap.h \
+		 sccp_helpers.h
 
 osmo_hnbgw_SOURCES = hnbap_encoder.c hnbap_decoder.c hnbap_common.c \
 		     rua_encoder.c rua_decoder.c rua_common.c \
diff --git a/src/hnbap/Makefile.am b/src/hnbap/Makefile.am
index e152587..0362871 100644
--- a/src/hnbap/Makefile.am
+++ b/src/hnbap/Makefile.am
@@ -236,7 +236,7 @@
 
 noinst_LIBRARIES=libosmo-asn1-hnbap.a
 libosmo_asn1_hnbap_a_SOURCES=$(ASN_MODULE_SOURCES)
-include_HEADERS = $(ASN_MODULE_INC)
+noinst_HEADERS = $(ASN_MODULE_INC)
 libosmo_asn1_hnbap_a_LIBADD=$(ASN1C_LDADD)
 
 regen: regenerate-from-asn1-source
diff --git a/src/rua/Makefile.am b/src/rua/Makefile.am
index cb13a1c..9e3cfb6 100644
--- a/src/rua/Makefile.am
+++ b/src/rua/Makefile.am
@@ -76,7 +76,7 @@
 
 noinst_LIBRARIES=libosmo-asn1-rua.a
 libosmo_asn1_rua_a_SOURCES=$(ASN_MODULE_SOURCES)
-include_HEADERS=$(ASN_MODULES_INC)
+noinst_HEADERS=$(ASN_MODULE_INC)
 libosmo_asn1_rua_a_LIBADD=$(ASN1C_LDADD)
 
 regen: regenerate-from-asn1-source
diff --git a/src/tests/Makefile.am b/src/tests/Makefile.am
index bcab7d4..122c663 100644
--- a/src/tests/Makefile.am
+++ b/src/tests/Makefile.am
@@ -1,16 +1,16 @@
-AM_CFLAGS = $(OSMOVTY_CFLAGS) $(OSMOCORE_CFLAGS) $(OSMOGSM_CFLAGS) $(OSMONETIF_CFLAGS) $(ASN1C_CFLAGS) $(OSMOSIGTRAN_CFLAGS) -g -I$(top_builddir)/src -I$(top_builddir)/src/hnbap/
+AM_CFLAGS = $(OSMOVTY_CFLAGS) $(OSMOCORE_CFLAGS) $(OSMOGSM_CFLAGS) $(OSMONETIF_CFLAGS) $(ASN1C_CFLAGS) $(OSMOSIGTRAN_CFLAGS) -g -I$(top_srcdir)/src -I$(top_srcdir)/src/hnbap/
 
 COMMON_LIBS = $(OSMOVTY_LIBS) $(OSMOCORE_LIBS) $(OSMOGSM_LIBS) $(ASN1C_LIBS) $(OSMOSIGTRAN_LIBS) -lsctp
 
 check_PROGRAMS = test-ranap test-helpers test-hnbap hnb-test dummy-cn
 
-HNBAP_FILES = $(top_builddir)/src/hnbap_common.c $(top_builddir)/src/hnbap_decoder.c $(top_builddir)/src/hnbap_encoder.c
-RUA_FILES = $(top_builddir)/src/rua_common.c $(top_builddir)/src/rua_decoder.c $(top_builddir)/src/rua_encoder.c
+HNBAP_FILES = $(top_srcdir)/src/hnbap_common.c $(top_srcdir)/src/hnbap_decoder.c $(top_srcdir)/src/hnbap_encoder.c
+RUA_FILES = $(top_srcdir)/src/rua_common.c $(top_srcdir)/src/rua_decoder.c $(top_srcdir)/src/rua_encoder.c
 
 test_helpers_SOURCES = test-helpers.c
 test_helpers_LDADD = $(COMMON_LIBS) $(top_builddir)/src/libosmo-ranap.la
 
-test_hnbap_SOURCES = $(top_builddir)/src/hnbap_common.c $(top_builddir)/src/hnbap_decoder.c test-hnbap.c test_common.c
+test_hnbap_SOURCES = $(top_srcdir)/src/hnbap_common.c $(top_srcdir)/src/hnbap_decoder.c test-hnbap.c test_common.c
 test_hnbap_LDADD = $(COMMON_LIBS) $(top_builddir)/src/hnbap/libosmo-asn1-hnbap.a $(top_builddir)/src/libosmo-ranap.la
 
 hnb_test_SOURCES = $(HNBAP_FILES) $(RUA_FILES) hnb-test.c rua_helper.c test_common.c