cmd/go: do not require a valid archChar when using -compiler gccgo

Fixes #7152.

R=iant, rsc, gobot
CC=golang-codereviews
https://golang.org/cl/54790044

diff --git a/src/cmd/go/build.go b/src/cmd/go/build.go
index c78f228105690a0c998bb965f5b140faf9080fd8..bfadec68ea76e890a7930078ed49b1935a37f357 100644 (file)
--- a/src/cmd/go/build.go
+++ b/src/cmd/go/build.go
@@ -350,7 +350,12 @@ func init() {
        var err error
        archChar, err = build.ArchChar(goarch)
        if err != nil {
-               fatalf("%s", err)
+               if _, isgc := buildToolchain.(gcToolchain); isgc {
+                       fatalf("%s", err)
+               }
+               // archChar is only required for gcToolchain, if we're using
+               // another toolchain leave it blank.
+               archChar = ""
        }
 }