mac: Make `find_sdk.py --print_sdk_path` much faster.

build/mac/find_sdk.py

Index: build/mac/find_sdk.py
diff --git a/build/mac/find_sdk.py b/build/mac/find_sdk.py
index ce23524c0fd57631722d643e7e210f292afe5c1d..618c0f57487e78aaccd294e525309909a167dbb8 100755
--- a/build/mac/find_sdk.py
+++ b/build/mac/find_sdk.py
@@ -52,16 +52,9 @@ def main():
   if job.returncode != 0:
     print >> sys.stderr, out
     print >> sys.stderr, err
-    raise Exception(('Error %d running xcode-select, you might have to run '
-      '|sudo xcode-select --switch /Applications/Xcode.app/Contents/Developer| '
-      'if you are using Xcode 4.') % job.returncode)
-  # The Developer folder moved in Xcode 4.3.
-  xcode43_sdk_path = os.path.join(
+    raise Exception('Error %d running xcode-select' % job.returncode)
+  sdk_dir = os.path.join(
       out.rstrip(), 'Platforms/MacOSX.platform/Developer/SDKs')
-  if os.path.isdir(xcode43_sdk_path):
-    sdk_dir = xcode43_sdk_path
-  else:
-    sdk_dir = os.path.join(out.rstrip(), 'SDKs')
   sdks = [re.findall('^MacOSX(10\.\d+)\.sdk$', s) for s in os.listdir(sdk_dir)]
   sdks = [s[0] for s in sdks if s]  # [['10.5'], ['10.6']] => ['10.5', '10.6']
   sdks = [s for s in sdks  # ['10.5', '10.6'] => ['10.6']
@@ -85,8 +78,8 @@ def main():
     return min_sdk_version
 
   if options.print_sdk_path:
-    print subprocess.check_output(['xcodebuild', '-version', '-sdk',
-                                   'macosx' + best_sdk, 'Path']).strip()
+    print subprocess.check_output(
+        ['xcrun', '-sdk', 'macosx' + best_sdk, '--show-sdk-path']).strip()
 
   return best_sdk