gc: small fixes for printing.

mark OADDR inserted by typecheck as implicit
OCOPY takes ->left and ->right, not ->list
OMAKE*'s can all have arguments
precedence for OIND was initalized twice

fixes #2414

R=rsc, dave
CC=golang-dev
https://golang.org/cl/5319065
diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index 87a8d78..d2268e6 100644
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -745,6 +745,7 @@
 		defaultlit(&n->right->right, T);
 		if(isfixedarray(n->left->type)) {
 			n->left = nod(OADDR, n->left, N);
+			n->left->implicit = 1;
 			typecheck(&n->left, top);
 		}
 		if(n->right->left != N) {