[libfuzzer] store custom options in .GN build target instead of a separate file.

testing/libfuzzer/tests/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 #
 # Fuzzing Infrastructure Tests
 
 import("//testing/test.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 
 test("libfuzzer_tests") {
@@ skipping 19 matching lines @@
   sources = [
     "../fuzzers/empty_fuzzer.cc",
   ]
   dict = "test.dict"
 }
 
 fuzzer_test("test_config_only") {
   sources = [
     "../fuzzers/empty_fuzzer.cc",
   ]
-  libfuzzer_options = "fuzzer_config_only_test.options"
+  libfuzzer_options = [
+    "some_test_option=test_value",
+    "max_len=1024",
+  ]
 }
 
 fuzzer_test("test_config_and_dict") {
   sources = [
     "../fuzzers/empty_fuzzer.cc",
   ]
   dict = "test.dict"
-  libfuzzer_options = "fuzzer_config_and_dict_test.options"
+  libfuzzer_options = [
+    "max_len=random(1337, 31337)",
+    "timeout   =   666",
+    "use_traces=1",
+  ]
 }
 
 fuzzer_test("test_dict_from_subdir") {
   sources = [
     "../fuzzers/empty_fuzzer.cc",
   ]
   dict = "dicts_subdir/test_subdir.dict"
 }
 
 copy("check_fuzzer_config") {
   sources = [
     "check_fuzzer_config.py",
   ]
   outputs = [
     "$root_build_dir/check_fuzzer_config.py",
   ]
 }