// isUnneededSSARewriteFile reports whether srcFile is a
// src/cmd/compile/internal/ssa/rewriteARCHNAME.go file for an
// architecture that isn't for the given GOARCH.
//
// When unneeded is true archCaps is the rewrite base filename without
// the "rewrite" prefix or ".go" suffix: AMD64, 386, ARM, ARM64, etc.
func isUnneededSSARewriteFile(srcFile, goArch string) (archCaps string, unneeded bool) {