new test for deprecated warnings

[[Imported from SVN: r1114]]

m4/dune_deprecated.m4

+# $Id$
+
+# Check for the right way to create the deprecated warning
+
+AC_DEFUN([DUNE_CHECKDEPRECATED],[
+	AC_MSG_CHECKING([for __attribute__((deprecated))])
+	AC_TRY_COMPILE([int foo() __attribute__((deprecated));
+                    int foo() {};],[],
+				   [DUNE_DEPRECATED="__attribute__((deprecated))"
+                    AC_MSG_RESULT(yes)],
+				   [DUNE_DEPRECATED=""
+                    AC_MSG_RESULT(no)])
+
+    AC_DEFINE_UNQUOTED(DUNE_DEPRECATED, $DUNE_DEPRECATED,
+                      [how to create a deprecated warning])
+])