Don't check includes in generate_jar_jni target

'gn check' for ui/gl:* in an android build currently fails with the
error message:

ERROR at //base/android/jni_generator/jni_generator_helper.h:11:11: Include not allowed.
          ^-------------------------
It is not in any dependency of //ui/gl:surface_jni_headers__jni_Surface
The include file is in the target(s):
  //base:base
which should somehow be reachable from //ui/gl:surface_jni_headers__jni_Surface

This target does not produce files that compile, so checking includes is
less useful.

R=brettw@chromium.org

Review URL: https://codereview.chromium.org/961033003

Cr-Commit-Position: refs/heads/master@{#318983}

build/config/android/rules.gni

@@ -160,6 +160,8 @@ template("generate_jar_jni") {
     jni_target_name = "${target_name}__jni_${classname}"
     jni_actions += [ ":$jni_target_name" ]
     action(jni_target_name) {
+      # The sources aren't compiled so don't check their dependencies.
+      check_includes = false
       depfile = "$target_gen_dir/$target_name.d"
       script = "//base/android/jni_generator/jni_generator.py"
       sources = [