eth/tracers: fix minor off-by-one error (ethereum#16879)

* tracing: fix minor off-by-one error

* tracers: go generate

Author: holiman

eth/tracers/internal/tracers/4byte_tracer.js

@@ -78,7 +78,7 @@
 	// the final result of the tracing.
 	result: function(ctx) {
 		// Save the outer calldata also
-		if (ctx.input.length > 4) {
+		if (ctx.input.length >= 4) {
 			this.store(slice(ctx.input, 0, 4), ctx.input.length-4)
 		}
 		return this.ids;