Initial device java support

First pass at java support for the device.  Adds desugar before
dx, and passes javalib.jar to make.

Test: m -j checkbuild
Change-Id: I3138d943bc4867a52c3fce8fbdb597773793988d

java/config/config.go

@@ -68,6 +68,7 @@ func init() {
 	pctx.StaticVariable("MergeZipsCmd", filepath.Join("${bootstrap.ToolDir}", "merge_zips"))
 	pctx.HostBinToolVariable("DxCmd", "dx")
 	pctx.HostJavaToolVariable("JarjarCmd", "jarjar.jar")
+	pctx.HostJavaToolVariable("DesugarJar", "desugar.jar")
 
 	pctx.VariableFunc("JavacWrapper", func(config interface{}) (string, error) {
 		if override := config.(android.Config).Getenv("JAVAC_WRAPPER"); override != "" {