Fix android.Expand and ninja escaping

RuleBuilder does its own ninja escaping, so values that will be
passed to RuleBuilder must not be pre-escaped.  Add a new
android.ExpandNinjaEscaped method that explicitly handles ninja
escaping.  Some of the expansion functions return ninja values
(like "${in}") that need to stay unescaped, so add a bool return
value to the expansion function in android.ExpandNinjaEscaped.

Test: expand_test.go
Change-Id: Ib03d4db38b5e3e5bffbd87acf14f55e276a53d04
diff --git a/genrule/genrule.go b/genrule/genrule.go
index b0657ff..411da05 100644
--- a/genrule/genrule.go
+++ b/genrule/genrule.go
@@ -284,12 +284,12 @@
 
 	referencedDepfile := false
 
-	rawCommand, err := android.Expand(task.cmd, func(name string) (string, error) {
+	rawCommand, err := android.ExpandNinjaEscaped(task.cmd, func(name string) (string, bool, error) {
 		// report the error directly without returning an error to android.Expand to catch multiple errors in a
 		// single run
-		reportError := func(fmt string, args ...interface{}) (string, error) {
+		reportError := func(fmt string, args ...interface{}) (string, bool, error) {
 			ctx.PropertyErrorf("cmd", fmt, args...)
-			return "SOONG_ERROR", nil
+			return "SOONG_ERROR", false, nil
 		}
 
 		switch name {
@@ -304,19 +304,19 @@
 				return reportError("default label %q has multiple files, use $(locations %s) to reference it",
 					firstLabel, firstLabel)
 			}
-			return locationLabels[firstLabel][0], nil
+			return locationLabels[firstLabel][0], false, nil
 		case "in":
-			return "${in}", nil
+			return "${in}", true, nil
 		case "out":
-			return "__SBOX_OUT_FILES__", nil
+			return "__SBOX_OUT_FILES__", false, nil
 		case "depfile":
 			referencedDepfile = true
 			if !Bool(g.properties.Depfile) {
 				return reportError("$(depfile) used without depfile property")
 			}
-			return "__SBOX_DEPFILE__", nil
+			return "__SBOX_DEPFILE__", false, nil
 		case "genDir":
-			return "__SBOX_OUT_DIR__", nil
+			return "__SBOX_OUT_DIR__", false, nil
 		default:
 			if strings.HasPrefix(name, "location ") {
 				label := strings.TrimSpace(strings.TrimPrefix(name, "location "))
@@ -327,7 +327,7 @@
 						return reportError("label %q has multiple files, use $(locations %s) to reference it",
 							label, label)
 					}
-					return paths[0], nil
+					return paths[0], false, nil
 				} else {
 					return reportError("unknown location label %q", label)
 				}
@@ -337,7 +337,7 @@
 					if len(paths) == 0 {
 						return reportError("label %q has no files", label)
 					}
-					return strings.Join(paths, " "), nil
+					return strings.Join(paths, " "), false, nil
 				} else {
 					return reportError("unknown locations label %q", label)
 				}