Remove check for Tailscale toolchain.

Broke the F-Droid build.
Update Dockerfile to use Go 1.17rc1 to verify that as a fix.

Signed-off-by: Denton Gentry <dgentry@tailscale.com>

Dockerfile

@@ -32,9 +32,9 @@ RUN echo y | $ANDROID_HOME/tools/bin/sdkmanager 'build-tools;28.0.3'
 
 # Get Go stable release
 WORKDIR $HOME
-ARG GO_VERSION=1.16.5
+ARG GO_VERSION=1.17rc1
 RUN curl -O https://storage.googleapis.com/golang/go${GO_VERSION}.linux-amd64.tar.gz
-RUN echo "b12c23023b68de22f74c0524f10b753e7b08b1504cb7e417eccebdd3fae49061  go${GO_VERSION}.linux-amd64.tar.gz" | sha256sum -c
+RUN echo "bfbd3881a01ca3826777b1c40f241acacd45b14730d373259cd673d74e15e534  go${GO_VERSION}.linux-amd64.tar.gz" | sha256sum -c
 RUN tar -xzf go${GO_VERSION}.linux-amd64.tar.gz && mv go goroot
 ENV GOROOT $HOME/goroot
 ENV PATH $PATH:$GOROOT/bin:$HOME/bin:$ANDROID_HOME/platform-tools

Makefile

@@ -31,7 +31,6 @@ tag_release:
 	git tag -a "$(VERSION_LONG)"
 
 $(DEBUG_APK):
-	(go version | grep -- "-ts") || (echo Must set have Tailscale production toolchain in PATH; exit 1)
 	mkdir -p android/libs
 	go run gioui.org/cmd/gogio -buildmode archive -target android -appid $(APPID) -o $(AAR) github.com/tailscale/tailscale-android/cmd/tailscale
 	(cd android && ./gradlew assemblePlayDebug)
@@ -39,7 +38,6 @@ $(DEBUG_APK):
 	
 # This target is also used by the F-Droid builder.
 release_aar:
-	(go version | grep -- "-ts") || (echo Must set have Tailscale production toolchain in PATH; exit 1)
 	mkdir -p android/libs
 	go run gioui.org/cmd/gogio -ldflags "-X tailscale.com/version.Long=$(VERSIONNAME) -X tailscale.com/version.Short=$(VERSIONNAME_SHORT) -X tailscale.com/version.GitCommit=$(TAILSCALE_COMMIT) -X tailscale.com/version.ExtraGitCommit=$(OUR_VERSION)" -tags xversion -buildmode archive -target android -appid $(APPID) -o $(AAR) github.com/tailscale/tailscale-android/cmd/tailscale