misc: check for libdbi, mandatory library dependency
Otherwise, openbsc fails to compile:
CC db.o
db.c:29:21: error: dbi/dbi.h: File does not exists
diff --git a/openbsc/configure.in b/openbsc/configure.in
index 1d2db88..4cd1952 100644
--- a/openbsc/configure.in
+++ b/openbsc/configure.in
@@ -49,6 +49,7 @@
dnl checks for header files
AC_HEADER_STDC
AC_CHECK_HEADERS(dahdi/user.h,,AC_MSG_WARN(DAHDI input driver will not be built))
+AC_CHECK_HEADERS(dbi/dbd.h,,AC_MSG_ERROR(DBI library is not installed))
dnl Checks for typedefs, structures and compiler characteristics