rspro_util: Add header file

Change-Id: I2f66531008943fa6bdc3c286aee2afd254384018
diff --git a/src/Makefile.am b/src/Makefile.am
index f1731fa..06e4311 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -11,7 +11,7 @@
 			  $(ASN1C_LIBS) rspro/libosmo-asn1-rspro.la
 libosmo_rspro_la_SOURCES = rspro_util.c rspro_client.c
 
-noinst_HEADERS = bankd.h internal.h
+noinst_HEADERS = bankd.h internal.h rspro_util.h
 
 bin_PROGRAMS = pcsc_test remsim-bankd