cmd/compile: make inlining intrinsics cost one

We were assigning a cost of 2 for intrinsics:
One when we recognized an intrinsic,
and one for the OCALLFUNC node.

I believe that the intent was that intrinsics should
cost 1, since they are typically an arithmetic op,
and because they tend to occur in performance-sensitive code.
(Not that any of this is particularly principled right now.)

Stop charging when we recognize an intrinsic;
let the OCALLFUNC node cover the cost.

This has a negligible impact on std+cmd.

Change-Id: Ie6ae5c18da3ae7e40aec425aed95c6999c2831a1
Reviewed-on: https://go-review.googlesource.com/c/go/+/221357
Run-TryBot: Josh Bleecher Snyder <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Matthew Dempsky <[email protected]>

Author: josharian

src/cmd/compile/internal/gc/inl.go

@@ -321,7 +321,7 @@ func (v *hairyVisitor) visit(n *Node) bool {
 		}
 
 		if isIntrinsicCall(n) {
-			v.budget--
+			// Treat like any other node.
 			break
 		}