[tools/fuchsia] Update for upstream flag rename in local-sdk.py

The '--modules' flag to gen.py was renamed '--packages'.

Bug: 707031
Change-Id: I04cbae76eacf0a9c593fdf1d375c84c25fbee088
Reviewed-on: https://chromium-review.googlesource.com/721887Reviewed-by: Scott Graham <scottmg@chromium.org>
Commit-Queue: James Robinson <jamesr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#509240}

tools/fuchsia/local-sdk.py

@@ -32,8 +32,8 @@ def EnsureEmptyDir(path):
 
 def BuildForArch(arch):
   Run('scripts/build-zircon.sh', '-t', arch)
-  Run('packages/gn/gen.py', '--target_cpu=' + arch, '--modules=packages/gn/sdk',
-      '--ignore-skia', '--release')
+  Run('packages/gn/gen.py', '--target_cpu=' + arch,
+      '--packages=packages/gn/sdk','--ignore-skia', '--release')
   Run('buildtools/ninja', '-C', 'out/release-' + arch)