This patch to the Go frontend sets DECL_NAMELESS for temporary
variables.  This is consistent with what create_tmp_var does, but is
used for cases where we can't use create_tmp_var.  Bootstrapped and
ran Go testsuite on x86_64-pc-linux-gnu.  Committed to mainline.

Ian

* go-gcc.cc (Gcc_backend::static_chain_variable): Set
DECL_NAMELESS on the new decl.
(Gcc_backend::temporary_variable): Likewise.
(Gcc_backend::function): Set DECL_NAMELESS on the result decl.