[release/1.4.11] Makefile, build: move cross compilation into ci.go

(cherry picked from commit 8c23f20c68)

build/ci.go

@@ -28,6 +28,7 @@ Available commands are:
    archive    [ -type zip|tar ]                        -- archives build artefacts
    importkeys                                          -- imports signing keys from env
    debsrc     [ -sign key-id ] [ -upload dest ]        -- creates a debian source package
+   xgo        [ options ]                              -- cross builds according to options
 
 For all commands, -n prevents execution of external programs (dry run mode).
 
@@ -121,6 +122,8 @@ func main() {
 		doDebianSource(os.Args[2:])
 	case "travis-debsrc":
 		doTravisDebianSource(os.Args[2:])
+	case "xgo":
+		doXgo(os.Args[2:])
 	default:
 		log.Fatal("unknown command ", os.Args[1])
 	}
@@ -463,3 +466,32 @@ func stageDebianSource(tmpdir string, meta debMetadata) (pkgdir string) {
 
 	return pkgdir
 }
+
+// Cross compilation
+
+func doXgo(cmdline []string) {
+	// Make sure xgo is available for cross compilation
+	gogetxgo := goTool("get", "github.com/karalabe/xgo")
+	build.MustRun(gogetxgo)
+
+	// Execute the actual cross compilation
+	pkg := cmdline[len(cmdline)-1]
+	args := append(cmdline[:len(cmdline)-1], makeBuildFlags("")...)
+
+	build.MustRun(xgoTool(append(args, pkg)...))
+}
+
+func xgoTool(args ...string) *exec.Cmd {
+	cmd := exec.Command(filepath.Join(GOBIN, "xgo"), args...)
+	cmd.Env = []string{
+		"GOPATH=" + build.GOPATH(),
+		"GOBIN=" + GOBIN,
+	}
+	for _, e := range os.Environ() {
+		if strings.HasPrefix(e, "GOPATH=") || strings.HasPrefix(e, "GOBIN=") {
+			continue
+		}
+		cmd.Env = append(cmd.Env, e)
+	}
+	return cmd
+}

build/flags.sh

@@ -1,22 +0,0 @@
-#!/bin/sh
-
-set -e
-
-if [ ! -f "build/env.sh" ]; then
-    echo "$0 must be run from the root of the repository."
-    exit 2
-fi
-
-# Since Go 1.5, the separator char for link time assignments
-# is '=' and using ' ' prints a warning. However, Go < 1.5 does
-# not support using '='.
-sep=$(go version | awk '{ if ($3 >= "go1.5" || index($3, "devel")) print "="; else print " "; }' -)
-
-# set gitCommit when running from a Git checkout.
-if [ -f ".git/HEAD" ]; then
-    echo "-ldflags '-X main.gitCommit$sep$(git rev-parse HEAD)'"
-fi
-
-if [ ! -z "$GO_OPENCL" ]; then
-   echo "-tags opencl"
-fi