Do not render unnecessary arguments to the console.

When build dependencies were stale, this incorrect message was shown:

```
Build deps are stale. Please run tools/install-build-deps
/Users/octaviant/Development/perfetto/out/ui/.check_deps --ui
```
Instead of:

```
Build deps are stale. Please run tools/install-build-deps --ui
```

Change-Id: I0519659c2ee49d4b5083fcfabe3b7eef2d15d400
diff --git a/ui/build.js b/ui/build.js
index 9d1a7f5..28f0456 100644
--- a/ui/build.js
+++ b/ui/build.js
@@ -159,7 +159,8 @@
 
   // Check that deps are current before starting.
   const installBuildDeps = pjoin(ROOT_DIR, 'tools/install-build-deps');
-  const depsArgs = ['--check-only', pjoin(cfg.outDir, '.check_deps'), '--ui'];
+  const checkDepsPath = pjoin(cfg.outDir, '.check_deps');
+  const depsArgs = [`--check-only=${checkDepsPath}`, '--ui'];
   exec(installBuildDeps, depsArgs);
 
   console.log('Entering', cfg.outDir);