c-common.def (FILE_STMT): New code.

        * c-common.def (FILE_STMT): New code.
        * c-common.c (statement_code_p): It's a statement.
        * c-common.h (stmt_tree_s): Add x_last_filename.
        (FILE_STMT_FILENAME_NODE, FILE_STMT_FILENAME): New macros.
        (last_expr_filename): New macro.
        * c-semantics.c (begin_stmt_tree): Initialize it.
        (add_stmt): If the filename changed, also insert a
        FILE_STMT.
        (expand_stmt): Handle seeing one.

From-SVN: r48881