Improve detection of resolv.h on versions of Darwin, FreeBSD and Solaris

(this requires post-2.13 autoconf, but 2.13 ignores it gracefully)

Author: Marko Karppinen

configure.in

@@ -326,7 +326,15 @@ sys/wait.h \
 unistd.h \
 unix.h \
 utime.h \
-)
+,,,[
+$ac_includes_default
+#if HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+#if HAVE_ARPA_NAMESER_H
+#include <arpa/nameser.h>
+#endif
+])
 
 dnl Checks for typedefs, structures, and compiler characteristics.
 AC_STRUCT_TM