Support the 'host' conditional in androidbp

Change-Id: I01eaa1ad2e05aaf8cbf00286d7272d0f45bb18aa

androidbp/cmd/androidbp.go

@@ -271,7 +271,7 @@ func (w *androidMkWriter) parsePropsAndWriteModule(module *Module) {
 		} else if "target" == prop.Name.Name {
 			props := w.lookupMap(prop.Value)
 			standardProps = append(standardProps, translateTargetConditionals(props, disabledBuilds, module.isHostRule)...)
-		} else if "host_supported" == prop.Name.Name {
+		} else if _, ok := ignoredProperties[prop.Name.Name]; ok {
 		} else {
 			standardProps = append(standardProps, fmt.Sprintf("# ERROR: Unsupported property %s", prop.Name.Name))
 		}

androidbp/cmd/soong.go

@@ -71,6 +71,10 @@ var rewriteProperties = map[string]struct {
 	"suffix":              {"LOCAL_MODULE_STEM", prependLocalModule},
 }
 
+var ignoredProperties = map[string]bool{
+	"host_supported": true,
+}
+
 var moduleTypeToRule = map[string]string{
 	"cc_library_shared":        "BUILD_SHARED_LIBRARY",
 	"cc_library_static":        "BUILD_STATIC_LIBRARY",
@@ -97,6 +101,7 @@ var suffixProperties = map[string]map[string]string{
 }
 
 var hostScopedPropertyConditionals = map[string]string{
+	"host":        "",
 	"darwin":      "ifeq ($(HOST_OS), darwin)",
 	"not_darwin":  "ifneq ($(HOST_OS), darwin)",
 	"windows":     "ifeq ($(HOST_OS), windows)",