devex: manage devtools in a project-local subdirectory + cleanup README (#829)

internal/platformtest/tests/gen/wrapper.bash

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+set -euo pipefail
+set -x
+
+source ../../../build/go_install_host_tool.source
+
+GOOS=$GOHOSTOS GOARCH=$GOHOSTARCH go run ./gen ./

internal/platformtest/tests/tests.go

@@ -13,4 +13,4 @@ func (c Case) String() string {
 	return runtime.FuncForPC(reflect.ValueOf(c).Pointer()).Name()
 }
 
-//go:generate go run ./gen github.com/zrepl/zrepl/platformtest/tests
+//go:generate ./gen/wrapper.bash