[Android] Remove var capture in TVM_SOURCE_DIR (#2538)

This PR fixes the TVM_SOURCE_DIR parsing issue on Windows.

Author: MasterJH5574

android/mlc4j/prepare_libs.py

@@ -2,8 +2,8 @@
 
 import argparse
 import os
-import sys
 import subprocess
+import sys
 from pathlib import Path
 
 from mlc_llm.support import logging
@@ -22,7 +22,7 @@ def run_cmake(mlc4j_path: Path):
     logger.info("Running cmake")
     # use pathlib so it is cross platform
     android_ndk_path = (
-        Path(os.environ['ANDROID_NDK']) / "build"/ "cmake"/ "android.toolchain.cmake"
+        Path(os.environ["ANDROID_NDK"]) / "build" / "cmake" / "android.toolchain.cmake"
     )
     cmd = [
         "cmake",
@@ -60,7 +60,7 @@ def run_cmake_build():
         "tvm4j_runtime_packed",
         "--config",
         "release",
-        f"-j{os.cpu_count()}"
+        f"-j{os.cpu_count()}",
     ]
     subprocess.run(cmd, check=True, env=os.environ)
 
@@ -93,7 +93,7 @@ def main(mlc_llm_source_dir: Path):
     if "TVM_SOURCE_DIR" in os.environ:
         logger.info('Set TVM_SOURCE_DIR to "%s"', os.environ["TVM_SOURCE_DIR"])
         with open("config.cmake", "w", encoding="utf-8") as file:
-            print("set(TVM_SOURCE_DIR ${%s})" % os.environ["TVM_SOURCE_DIR"], file=file)
+            print("set(TVM_SOURCE_DIR %s)" % os.environ["TVM_SOURCE_DIR"], file=file)
 
     # - Run cmake, build and install
     run_cmake(mlc_llm_source_dir / "android" / "mlc4j")