configure.ac: set C and C++ dialects
Make sure that the compiler always assumes the same C dialect, to
prevent unexpected compiler errors when building with older compilers
(on other Linux distrubtions like in OBS, or in docker).
Use gnu89 and gnu++03, because that is what the code currently compiles
with.
Related: https://lists.osmocom.org/pipermail/openbsc/2019-September/013030.html
Related: OS#3598
Change-Id: Ia57ba101627e3cc0babeca82631e207a3e2e0960
diff --git a/configure.ac b/configure.ac
index 5ecd133..2f29047 100644
--- a/configure.ac
+++ b/configure.ac
@@ -9,6 +9,9 @@
AM_INIT_AUTOMAKE([dist-bzip2])
AC_CONFIG_TESTDIR(tests)
+CXXFLAGS="$CXXFLAGS -std=gnu++03"
+CFLAGS="$CFLAGS -std=gnu89"
+
dnl kernel style compile messages
m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])