soong: Fix trailing comma for one-line modules

src/build/soong.ts

@@ -249,8 +249,10 @@ export function serializeModule(module: SoongModule) {
     serialized = `${type} ${serialized}`
     // Add trailing comma to last prop
     let serialLines = serialized.split('\n')
+    if (serialLines.length > 1) {
       serialLines[serialLines.length - 2] = serialLines.at(-2) + ','
       serialized = serialLines.join('\n')
+    }
 
     return serialized
 }