update_engine: Remove GPIO support.

We have not used GPIO since Jan 2013. This CL removes the GPIO handling code.
As a side effect, it also removes dependency on libudev.

BUG=chromium:221725
CQ-DEPEND=CL:199683
TEST=unittest
TEST=AU end2end test on real device from older version to a version that
has CL applied, then from that to another newer version (need not have
this CL applied).

Change-Id: I4352488ec360b44a44b137c40a3ae4ec35c6fe9d
Reviewed-on: https://chromium-review.googlesource.com/199626
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: Nam Nguyen <namnguyen@chromium.org>
Tested-by: Nam Nguyen <namnguyen@chromium.org>
diff --git a/http_fetcher_unittest.cc b/http_fetcher_unittest.cc
index dc00139..74c6a16 100644
--- a/http_fetcher_unittest.cc
+++ b/http_fetcher_unittest.cc
@@ -268,7 +268,7 @@
     proxy_resolver_.set_num_proxies(num_proxies);
     LibcurlHttpFetcher *ret = new
         LibcurlHttpFetcher(reinterpret_cast<ProxyResolver*>(&proxy_resolver_),
-                           &fake_system_state_, false);
+                           &fake_system_state_);
     // Speed up test execution.
     ret->set_idle_seconds(1);
     ret->set_retry_seconds(1);
@@ -317,7 +317,7 @@
         reinterpret_cast<ProxyResolver*>(&proxy_resolver_);
     MultiRangeHttpFetcher *ret =
         new MultiRangeHttpFetcher(
-            new LibcurlHttpFetcher(resolver, &fake_system_state_, false));
+            new LibcurlHttpFetcher(resolver, &fake_system_state_));
     ret->ClearRanges();
     ret->AddRange(0);
     // Speed up test execution.