build: use tar-ustar to allow paths longer than 99

Needed to fix these errors:

  tar: osmo-iuh-UNKNOWN-dirty/include/osmocom/ranap/RANAP_SourceeNodeB-ToTargeteNodeB-TransparentContainer.h: file name is too long (max 99); not dumped
  tar: osmo-iuh-UNKNOWN-dirty/include/osmocom/ranap/RANAP_LocationRelatedDataRequestTypeSpecificToGERANIuMode.h: file name is too long (max 99); not dumped
  tar: osmo-iuh-UNKNOWN-dirty/include/osmocom/ranap/RANAP_TargeteNodeB-ToSourceeNodeB-TransparentContainer.h: file name is too long (max 99); not dumped
  tar: osmo-iuh-UNKNOWN-dirty/include/osmocom/ranap/RANAP_Requested-RAB-Parameter-ExtendedGuaranteedBitrateList.h: file name is too long (max 99); not dumped

Change-Id: Id41bca92810a81ac50697c0230a6caef490b0ffd
diff --git a/configure.ac b/configure.ac
index c3a65d6..0c3ba3e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4,7 +4,10 @@
 
 LT_INIT
 
-AM_INIT_AUTOMAKE([foreign dist-bzip2 no-dist-gzip 1.6 subdir-objects])
+AM_INIT_AUTOMAKE([foreign dist-bzip2 no-dist-gzip 1.9 subdir-objects tar-ustar])
+dnl tar-ustar: some asn1 filenames surpass the 99 char limit of tar, so we need
+dnl to make tar allow longer filenames.
+
 AC_CONFIG_TESTDIR(src/tests)
 
 dnl kernel style compile messages