Change how the Android camput.arm asset is built to use make.go

Change-Id: I00a6e22ef088a173f78ffca83c984d915670180c

clients/android/assets/Makefile

@@ -1,6 +1,16 @@
+# To use this Makefile, first:
+#
+#   $ cd $GOROOT/src
+#   $ GOOS=linux GOARCH=arm ./make.bash
+#
+# TODO: have make.go bootstrap that above when necessary, running "go env" to find the GOROOT and
+# mirror it all into a separate writable GOROOT under $CAMROOT/tmp and bootstrap
+# it with "GOOS=linux GOARCH=arm make.bash".
 all:
-	GOROOT=$(HOME)/armgo GOOS=linux GOARCH=arm CGO_ENABLED=0 $(HOME)/armgo/bin/go build -o camput.arm --ldflags="-X camlistore.org/pkg/buildinfo.GitInfo "`../../../misc/gitversion` camlistore.org/cmd/camput
+	(cd ../../.. && go run make.go --os=linux --arch=arm --targets=camlistore.org/cmd/camput)
+	cp -p ../../../bin/linux_arm/camput camput.arm
 	../../../misc/gitversion > camput-version.txt
+	mkdir -p ../gen/org/camlistore
 	/bin/echo -n "package org.camlistore; public final class ChildProcessConfig { // " > ../gen/org/camlistore/ChildProcessConfig.java
 	openssl sha1 camput.arm >> ../gen/org/camlistore/ChildProcessConfig.java
 	/bin/echo "}" >> ../gen/org/camlistore/ChildProcessConfig.java

make.go

@@ -248,10 +248,21 @@ func main() {
 	}
 
 	if !*quiet {
+		// TODO: change this next line to call
+		// actualBinDir(binDir) instead. But the linker
+		// crashes (!!?!) right now if we do that.
+		// Bug to be filed once I'm off this plane.
 		log.Printf("Success. Binaries are in %s", binDir)
 	}
 }
 
+func actualBinDir(dir string) string {
+	if *buildARCH == runtime.GOARCH && *buildOS == runtime.GOOS {
+		return dir
+	}
+	return filepath.Join(dir, *buildOS+"_"+*buildARCH)
+}
+
 // Create an environment variable of the form key=value.
 func envPair(key, value string) string {
 	return fmt.Sprintf("%s=%s", key, value)