update: remove gcs storage driver build tags

GCS storage driver used to be conditionally built due to its being
outdated and basically unmaintained. Recently the driver has gone
through a rework and updates. Let's remove the build tag so we have less
headaches dealing with it and try keeping it up to date.

Signed-off-by: Milos Gajdos <milosthegajdos@gmail.com>

BUILDING.md

@@ -100,8 +100,6 @@ the environment variable `BUILDTAGS`.
 <dl>
 <dt>noresumabledigest</dt>
 <dd>Compiles without resumable digest support</dd>
-<dt>include_gcs</dt>
-<dd>Adds support for <a href="https://cloud.google.com/storage">Google Cloud Storage</a></dd>
 </dl>
 
 ### Local cloud storage environment

Dockerfile

@@ -22,7 +22,7 @@ RUN --mount=target=. \
 FROM base AS build
 ARG TARGETPLATFORM
 ARG LDFLAGS="-s -w"
-ARG BUILDTAGS="include_gcs"
+ARG BUILDTAGS=""
 RUN --mount=type=bind,target=/src \
     --mount=type=cache,target=/root/.cache/go-build \
     --mount=target=/go/pkg/mod,type=cache \

dockerfiles/lint.Dockerfile

@@ -3,7 +3,7 @@
 ARG GO_VERSION=1.20.12
 ARG ALPINE_VERSION=3.18
 ARG GOLANGCI_LINT_VERSION=v1.55.2
-ARG BUILDTAGS="include_gcs"
+ARG BUILDTAGS=""
 
 FROM golangci/golangci-lint:${GOLANGCI_LINT_VERSION}-alpine AS golangci-lint
 

registry/storage/driver/gcs/doc.go

@@ -1,3 +1,2 @@
-// Package gcs implements the Google Cloud Storage driver backend. Support can be
-// enabled by including the "include_gcs" build tag.
+// Package gcs implements the Google Cloud Storage driver backend.
 package gcs

registry/storage/driver/gcs/gcs.go

@@ -1,6 +1,3 @@
-//go:build include_gcs
-// +build include_gcs
-
 // Package gcs provides a storagedriver.StorageDriver implementation to
 // store blobs in Google cloud storage.
 //

registry/storage/driver/gcs/gcs_test.go

@@ -1,6 +1,3 @@
-//go:build include_gcs
-// +build include_gcs
-
 package gcs
 
 import (