Fix fuzzer build

Removes dependencies on gtest from fuzzer target. In turn this
implies removing gtest deps from base:test_support.
The fuzzer build has beeen failing in a very mysterious way for
a while (https://pastebin.com/1Ana2BnY).
The failure seems to go away by removing gtest dependencies
from the fuzzer targets.
I bisected the change to the point where I just removed the
googletest/googletest/src/gtest-all.cc from the gtest target.
I don't have a full explanation of what's happening. I can only
observe that when gtest is built as part of a fuzzer build, the
FuzzerDriver constructor fails with this https://pastebin.com/TeXPD5X9
while initializing it's piecewise_constant_distribution member.
The failure becomes more evident if building with is_debug=true.
I suspect some static initializer in gtest somehow corrupts the
state of <random> in a way that libfuzzer doesn't like.

Test: build and run trace_processor_fuzzer
Change-Id: Ic3da3625835644896705aa7443c1be6ec91069bc
diff --git a/Android.bp b/Android.bp
index 15e84a4..924cf8c 100644
--- a/Android.bp
+++ b/Android.bp
@@ -892,6 +892,7 @@
     "test/end_to_end_integrationtest.cc",
     "test/fake_producer.cc",
     "test/task_runner_thread.cc",
+    "test/task_runner_thread_delegates.cc",
     "test/test_helper.cc",
   ],
   shared_libs: [
@@ -4181,6 +4182,7 @@
     "test/end_to_end_integrationtest.cc",
     "test/fake_producer.cc",
     "test/task_runner_thread.cc",
+    "test/task_runner_thread_delegates.cc",
     "test/test_helper.cc",
   ],
   export_include_dirs: [
@@ -4206,6 +4208,7 @@
     "src/base/android_task_runner.cc",
     "src/base/test/test_task_runner.cc",
     "test/fake_producer.cc",
+    "test/task_runner_thread_delegates.cc",
   ],
   shared_libs: [
     "libprotobuf-cpp-lite",