cmd/dist: ignore _test.s files in bootstrap

Ignore all _test.s files in bootstrap, not only the ARM64 one.
They are for testing only.

Fixes #40855.

Change-Id: I00e6b4ab5349e317c9ad3a503997de85aed49373
Reviewed-on: https://go-review.googlesource.com/c/go/+/249018
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/dist/buildtool.go

@@ -113,14 +113,15 @@ var ignorePrefixes = []string{
 
 // File suffixes that use build tags introduced since Go 1.4.
 // These must not be copied into the bootstrap build directory.
+// Also igonore test files.
 var ignoreSuffixes = []string{
 	"_arm64.s",
-	"_arm64_test.s",
 	"_arm64.go",
 	"_riscv64.s",
 	"_riscv64.go",
 	"_wasm.s",
 	"_wasm.go",
+	"_test.s",
 }
 
 func bootstrapBuildTools() {