PR c/69405 - [6 Regression] ICE in c_tree_printer on an invalid

PR c/69405 - [6 Regression] ICE in c_tree_printer on an invalid

PR c/69405 - [6 Regression] ICE in c_tree_printer on an invalid
    __atomic_fetch_add

gcc/testsuite/ChangeLog:
2016-01-20  Martin Sebor  <msebor@redhat.com>

        PR c/69405
        * gcc.dg/sync-fetch.c: New test.

gcc/c-family/ChangeLog:
2016-01-20  Martin Sebor  <msebor@redhat.com>

        PR c/69405
        * c-common.c (sync_resolve_size): Avoid printing diagnostic about
        an incompatible argument when the argument isn't a valid tree node.

From-SVN: r232713