Add CoreDNS build

This adds CoreDNS and all relevant dependencies. Unused plugins are patched out
to prevent excessive dependencies and binary size.

Test Plan: `bazel build @com_github_coredns_coredns//:coredns`

X-Origin-Diff: phab/D614
GitOrigin-RevId: a897bc0e9f908218fd2f414d7e3b902c14e0a374
diff --git a/third_party/go/shelf.pb.text b/third_party/go/shelf.pb.text
index 9d77503..3e0eded 100644
--- a/third_party/go/shelf.pb.text
+++ b/third_party/go/shelf.pb.text
@@ -167,6 +167,13 @@
   semver: "v0.0.0-20190309065803-0b2ad9ac246b"
 >
 entry: <
+  import_path: "github.com/caddyserver/caddy"
+  version: "v1.0.5"
+  bazel_name: "com_github_caddyserver_caddy"
+  sum: "h1:5B1Hs0UF2x2tggr2X9jL2qOZtDXbIWQb9YLbmlxHSuM="
+  semver: "v1.0.5"
+>
+entry: <
   import_path: "github.com/cenkalti/backoff"
   version: "v0.0.0-20190506075156-2146c9339422"
   bazel_name: "com_github_cenkalti_backoff"
@@ -496,6 +503,13 @@
   semver: "v1.0.1"
 >
 entry: <
+  import_path: "github.com/coredns/coredns"
+  version: "v1.7.0"
+  bazel_name: "com_github_coredns_coredns"
+  sum: "h1:Tm2ZSdhTk+4okgjUp4K6KYzvBI2u34cdD4fKQRC4Eeo="
+  semver: "v1.7.0"
+>
+entry: <
   import_path: "github.com/coreos/go-iptables"
   version: "v0.4.2"
   bazel_name: "com_github_coreos_go_iptables"
@@ -622,6 +636,13 @@
   semver: "v1.0.0"
 >
 entry: <
+  import_path: "github.com/dnstap/golang-dnstap"
+  version: "v0.2.0"
+  bazel_name: "com_github_dnstap_golang_dnstap"
+  sum: "h1:+NrmP4mkaTeKYV7xJ5FXpUxRn0RpcgoQcsOCTS8WQPk="
+  semver: "v0.2.0"
+>
+entry: <
   import_path: "github.com/docker/distribution"
   version: "0d3efadf0154c2b8a4e7b6621fff9809655cc580"
   bazel_name: "com_github_docker_distribution"
@@ -783,6 +804,13 @@
   semver: "v0.0.0-20151013193312-d6023ce2651d"
 >
 entry: <
+  import_path: "github.com/farsightsec/golang-framestream"
+  version: "v0.0.0-20190425193708-fa4b164d59b8"
+  bazel_name: "com_github_farsightsec_golang_framestream"
+  sum: "h1:/iPdQppoAsTfML+yqFSq2EBChiEMnRkh5WvhFgtWwcU="
+  semver: "v0.0.0-20190425193708-fa4b164d59b8"
+>
+entry: <
   import_path: "github.com/fatih/camelcase"
   version: "v1.0.0"
   bazel_name: "com_github_fatih_camelcase"
@@ -797,6 +825,13 @@
   semver: "v1.7.0"
 >
 entry: <
+  import_path: "github.com/flynn/go-shlex"
+  version: "v0.0.0-20150515145356-3f9db97f8568"
+  bazel_name: "com_github_flynn_go_shlex"
+  sum: "h1:BHsljHzVlRcyQhjrss6TZTdY2VfCqZPbv5k3iBFa2ZQ="
+  semver: "v0.0.0-20150515145356-3f9db97f8568"
+>
+entry: <
   import_path: "github.com/friendsofgo/errors"
   version: "v0.9.2"
   bazel_name: "com_github_friendsofgo_errors"
@@ -1182,6 +1217,13 @@
   semver: "v1.9.5"
 >
 entry: <
+  import_path: "github.com/grpc-ecosystem/grpc-opentracing"
+  version: "v0.0.0-20180507213350-8e809c8a8645"
+  bazel_name: "com_github_grpc_ecosystem_grpc_opentracing"
+  sum: "h1:MJG/KsmcqMwFAkh8mTnAwhyKoB+sTAnY4CACC110tbU="
+  semver: "v0.0.0-20180507213350-8e809c8a8645"
+>
+entry: <
   import_path: "github.com/grpc/grpc"
   version: "v1.26.0"
   bazel_name: "com_github_grpc_grpc"
@@ -1301,6 +1343,13 @@
   semver: "v0.3.7"
 >
 entry: <
+  import_path: "github.com/infobloxopen/go-trees"
+  version: "v0.0.0-20190313150506-2af4e13f9062"
+  bazel_name: "com_github_infobloxopen_go_trees"
+  sum: "h1:d3VSuNcgTCn21dNMm8g412Fck/XWFmMj4nJhhHT7ZZ0="
+  semver: "v0.0.0-20190313150506-2af4e13f9062"
+>
+entry: <
   import_path: "github.com/insomniacslk/dhcp"
   version: "5dd7202f19711228cb4a51aa8b3415421c2edefe"
   bazel_name: "com_github_insomniacslk_dhcp"
@@ -1763,6 +1812,13 @@
   semver: "v1.5.1"
 >
 entry: <
+  import_path: "github.com/opentracing/opentracing-go"
+  version: "v1.1.0"
+  bazel_name: "com_github_opentracing_opentracing_go"
+  sum: "h1:pWlfV3Bxv7k65HYwkikxat0+s3pV4bsqf19k25Ur8rU="
+  semver: "v1.1.0"
+>
+entry: <
   import_path: "github.com/optiopay/kafka"
   version: "b5a758dbffc5786a8cac42703bd5d63f503bd008"
   bazel_name: "com_github_optiopay_kafka"