Set to correct working directory for shaderc build

Change-Id: Ib8e5d57b1856bc41fe533a2adf876b164a0b7f4b
diff --git a/build-android/build.py b/build-android/build.py
index 3e7593f..cb34512 100755
--- a/build-android/build.py
+++ b/build-android/build.py
@@ -134,7 +134,7 @@
 
   print('Building shader toolchain...')
   build_cmd = [
-    'bash', ndk_build, '-C', build_dir, jobs_arg(),
+    'bash', ndk_build, '-C', shaderc_dir, jobs_arg(),
     'APP_ABI=' + ' '.join(abis),
     # Use the prebuilt platforms and toolchains.
     'NDK_PLATFORMS_ROOT=' + platforms_root,
@@ -157,7 +157,7 @@
     '_NDK_TESTING_ALL_=yes'
   ]
 
-  subprocess.check_call(build_cmd, cwd=shaderc_dir)
+  subprocess.check_call(build_cmd)
   print('Finished shader toolchain build')
 
   build_cmd = [