deprecate building for mips (#14174)

Co-authored-by: zeripath <art27@cantab.net>

Makefile

@@ -584,7 +584,7 @@ release-linux: | $(DIST_DIRS)
 	@hash xgo > /dev/null 2>&1; if [ $$? -ne 0 ]; then \
 		GO111MODULE=off $(GO) get -u src.techknowlogick.com/xgo; \
 	fi
-	CGO_CFLAGS="$(CGO_CFLAGS)" GO111MODULE=off xgo -go $(XGO_VERSION) -dest $(DIST)/binaries -tags 'netgo osusergo $(TAGS)' -ldflags '-linkmode external -extldflags "-static" $(LDFLAGS)' -targets 'linux/amd64,linux/386,linux/arm-5,linux/arm-6,linux/arm64,linux/mips64le,linux/mips,linux/mipsle' -out gitea-$(VERSION) .
+	CGO_CFLAGS="$(CGO_CFLAGS)" GO111MODULE=off xgo -go $(XGO_VERSION) -dest $(DIST)/binaries -tags 'netgo osusergo $(TAGS)' -ldflags '-linkmode external -extldflags "-static" $(LDFLAGS)' -targets 'linux/amd64,linux/386,linux/arm-5,linux/arm-6,linux/arm64' -out gitea-$(VERSION) .
 ifeq ($(CI),drone)
 	cp /build/* $(DIST)/binaries
 endif