[DAHDI] build dahdi driver only if dahdi header is present
diff --git a/openbsc/configure.in b/openbsc/configure.in
index 6aa68d8..ff6a466 100644
--- a/openbsc/configure.in
+++ b/openbsc/configure.in
@@ -48,6 +48,8 @@
 
 dnl checks for header files
 AC_HEADER_STDC
+AC_CHECK_HEADERS(dahdi/user.h,,AC_MSG_WARN(DAHDI input driver will not be built))
+
 
 dnl Checks for typedefs, structures and compiler characteristics