fix(lib): respect rollupOptions.input in lib mode (#10116)

Author: lsdsjy

packages/vite/src/node/build.ts

@@ -373,7 +373,7 @@ async function doBuild(
 
   const resolve = (p: string) => path.resolve(config.root, p)
   const input = libOptions
-    ? resolve(libOptions.entry)
+    ? options.rollupOptions?.input || resolve(libOptions.entry)
     : typeof options.ssr === 'string'
     ? resolve(options.ssr)
     : options.rollupOptions?.input || resolve('index.html')