compiler: set captured variable address to nonescape until further flooded

    
    The escape analysis models closures by flowing captured variable
    address to the closure node. However, the escape state for the
    address expressions remained unset as ESCAPE_UNKNOWN. This
    caused later passes to conclude that the address escapes. Fix this by
    setting its escape state to ESCAPE_NONE first. If it escapes
    (because the closure escapes), the flood phase will set its
    escape state properly.
    
    Reviewed-on: https://go-review.googlesource.com/86240

From-SVN: r256411

gcc/go/gofrontend/MERGE

-7c5e4d67041e3529a055a923b2b9f5ef09aa72a3
+bea521d1d8688bea5b14b1ae2a03aec949f48a44
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

gcc/go/gofrontend/escape.cc

@@ -1774,9 +1774,7 @@ Escape_analysis_assign::expression(Expression** pexpr)
 	    for (; p != sce->vals()->end(); ++p)
 	      {
 		Node* enclosed_node = Node::make_node(*p);
-		Node::Escape_state* state =
-		  enclosed_node->state(this->context_, NULL);
-		state->loop_depth = this->context_->loop_depth();
+		this->context_->track(enclosed_node);
 		this->assign(closure_node, enclosed_node);
 	      }
 	  }