[Fuchsia] Make importing AEMU dependent on gclient args

Added checkout_aemu to gclient_gn_args.
Check checkout_aemu when generating runner scripts, and only download
AEMU if the value is true.

Bug: b/142756812
Change-Id: Ic08b0abe945703ee5d6cddbc661831bbbdce784d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1879819
Commit-Queue: Chong Gu <chonggu@google.com>
Reviewed-by: Kevin Marshall <kmarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710117}

DEPS

@@ -35,6 +35,7 @@ gclient_gn_args = [
   'checkout_nacl',
   'checkout_oculus_sdk',
   'checkout_openxr',
+  'checkout_aemu'
 ]
 
 

build/config/fuchsia/generate_runner_scripts.gni

@@ -7,6 +7,7 @@ assert(is_fuchsia)
 import("//build/config/chromecast_build.gni")
 import("//build/config/fuchsia/config.gni")
 import("//build/config/fuchsia/package.gni")
+import("//build/config/gclient_args.gni")
 import("//build/config/sysroot.gni")
 import("//build/util/generate_wrapper.gni")
 
@@ -95,7 +96,7 @@ template("fuchsia_package_runner") {
       "${boot_image_root}/qemu/zircon-a.zbi",
     ]
 
-    if (host_cpu == "x64" && target_cpu == "x64") {
+    if (checkout_aemu) {
       data += [ "${aemu_root}/" ]
     }