Restore support for ARMv5 platforms

changelog/unreleased/issue-4540

@@ -0,0 +1,9 @@
+Bugfix: Restore ARMv5 support for ARM binaries
+
+The official release binaries for restic 0.16.1 were accidentally built to
+require ARMv7. We have updated the build process to restore support for ARMv5.
+
+Please note that restic 0.17.0 will drop support for ARMv5 and require at least
+ARMv6.
+
+https://github.com/restic/restic/issues/4540

helpers/build-release-binaries/main.go

@@ -125,6 +125,9 @@ func build(sourceDir, outputDir, goos, goarch string) (filename string) {
 		"GOOS="+goos,
 		"GOARCH="+goarch,
 	)
+	if goarch == "arm" {
+		c.Env = append(c.Env, "GOARM=5")
+	}
 	verbose("run %v %v in %v", "go", c.Args, c.Dir)
 
 	err := c.Run()