Only use -race when -race is also given to build.go on the command line:
x86_64 musl targets do not support the Go race runtime.

--- a/build.go
+++ b/build.go
@@ -364,7 +364,7 @@
 
 	args := []string{"test", "-short", "-timeout", timeout, "-tags", "purego"}
 
-	if runtime.GOARCH == "amd64" {
+	if race && runtime.GOARCH == "amd64" {
 		switch runtime.GOOS {
 		case "darwin", "linux", "freebsd": // , "windows": # See https://github.com/golang/go/issues/27089
 			args = append(args, "-race")