vendor: only vendor on emitted binaries

Moves the vendor/ directory to cmd/vendor. Vendored binaries are built
from cmd/, which is backed by symlinks pointing back to repo root.

cmd/vendor/google.golang.org/grpc/coverage.sh

@@ -0,0 +1,47 @@
+#!/bin/bash
+
+set -e
+
+workdir=.cover
+profile="$workdir/cover.out"
+mode=set
+end2endtest="google.golang.org/grpc/test"
+
+generate_cover_data() {
+    rm -rf "$workdir"
+    mkdir "$workdir"
+
+    for pkg in "$@"; do
+        if [ $pkg == "google.golang.org/grpc" -o $pkg == "google.golang.org/grpc/transport" -o $pkg == "google.golang.org/grpc/metadata" -o $pkg == "google.golang.org/grpc/credentials" ]
+            then
+                f="$workdir/$(echo $pkg | tr / -)"
+                go test -covermode="$mode" -coverprofile="$f.cover" "$pkg"
+                go test -covermode="$mode" -coverpkg "$pkg" -coverprofile="$f.e2e.cover" "$end2endtest"
+        fi
+    done
+
+    echo "mode: $mode" >"$profile"
+    grep -h -v "^mode:" "$workdir"/*.cover >>"$profile"
+}
+
+show_cover_report() {
+    go tool cover -${1}="$profile"
+}
+
+push_to_coveralls() {
+    goveralls -coverprofile="$profile"
+}
+
+generate_cover_data $(go list ./...)
+show_cover_report func
+case "$1" in
+"")
+    ;;
+--html)
+    show_cover_report html ;;
+--coveralls)
+    push_to_coveralls ;;
+*)
+    echo >&2 "error: invalid option: $1" ;;
+esac
+rm -rf "$workdir"