title: Building Android msm-3.18 kernel fails on soong-cc-config test on setSdclangVars()
body: <p>I am trying to build msm-3.18 kernel for msm8996 (Android 8.0.0).
  When trying to build from Android source top directory, it fails on running tests.</p>
  
  <p>Following is the trace</p>
  
  <pre><code>FAILED: out/soong/.bootstrap/soong-cc-config/test/test.passed
  out/soong/.bootstrap/bin/gotestrunner -p ./build/soong/cc/config -f out/soong/.bootstrap/soong-cc-config/test/test.passed -- \ out/soong/.bootstrap/soong-cc-config/test/test -test.short
  panic: read /home/vagrant/android-msm: is a directory
  
  goroutine 1 [running]:
  android/soong/cc/config.setSdclangVars()
      /home/vagrant/android-msm/build/soong/cc/config/global.go:197 +0x20d4
  android/soong/cc/config.init.2()
      /home/vagrant/android-msm/build/soong/cc/config/global.go:169 +0xcc9
  android/soong/cc/config.init()
      /home/vagrant/android-msm/build/soong/cc/config/tidy_test.go:42 +0x3969
  main.init()
      /home/vagrant/android-msm/out/soong/.bootstrap/soong-cc-
  config/test/test.go:34 +0x4e
  ninja: build stopped: subcommand failed.
  15:22:17 soong bootstrap failed with: exit status 1
  make: *** [run_soong_ui] Error 1
  make: Leaving directory `/home/vagrant/android-msm'
  </code></pre>
  
  <p>I guess it has something to do with $SDCLANG_PATH but I need help</p>