cmd/compile: mention the AuxInt field for bounded shifts

This comment needs updating after moving the "bounded" mark from
Aux to AuxInt.

Change-Id: I924fb22a81fffcd6944b93f0e3357c3aa2c4c49e
Reviewed-on: https://go-review.googlesource.com/111880Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/compile/internal/ssa/gen/genericOps.go

@@ -100,7 +100,7 @@ var genericOps = []opData{
 	// For shifts, AxB means the shifted value has A bits and the shift amount has B bits.
 	// Shift amounts are considered unsigned.
 	// If arg1 is known to be less than the number of bits in arg0,
-	// then aux may be set to true.
+	// then auxInt may be set to 1.
 	// This enables better code generation on some platforms.
 	{name: "Lsh8x8", argLength: 2, aux: "Bool"}, // arg0 << arg1
 	{name: "Lsh8x16", argLength: 2, aux: "Bool"},