Add method to return whether current host order is little endian to quic_endian. Also add unittest for quic_endian.

Merge internal change: 149025657

[email protected]
BUG=

Review-Url: https://codereview.chromium.org/2729063002
Cr-Commit-Position: refs/heads/master@{#454572}
diff --git a/net/BUILD.gn b/net/BUILD.gn
index 5334ba8..63e6426 100644
--- a/net/BUILD.gn
+++ b/net/BUILD.gn
@@ -4481,6 +4481,7 @@
     "quic/core/quic_versions_test.cc",
     "quic/core/quic_write_blocked_list_test.cc",
     "quic/core/spdy_utils_test.cc",
+    "quic/platform/api/quic_endian_test.cc",
     "quic/platform/api/quic_estimate_memory_usage.h",
     "quic/platform/api/quic_hostname_utils_test.cc",
     "quic/platform/api/quic_lru_cache_test.cc",