+
+# since change #28654, _XOPEN_SOURCE symbol needs to be defined on aix 4.2
+# to avoid the following build error in perlio.c :
+# 1506-294 (S) Syntax error in expression on #if directive.
+#
+case "$osvers" in
+ 4.2.1.0)
+ ccflags="$ccflags -D_XOPEN_SOURCE"
+ # aix 4.2 does not have IPv6 support
+ d_inetpton='undef'
+ d_inetntop='undef'
+ ;;
+ esac