clang mac tot bots: Stop setting DEVELOPER_DIR.

After https://chromium-review.googlesource.com/c/chromium/tools/build/+/1744467
the clang mac tot bots should have a system Xcode install that we
want to use instead.

Bug: 976593,985971
Change-Id: I1bf0aaacf4f6485352b4741e6a263cbfbe7d4318
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1743104Reviewed-by: Hans Wennborg <hans@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#685525}

tools/clang/scripts/build.py

@@ -245,16 +245,6 @@ def MaybeDownloadHostGcc(args):
   args.gcc_toolchain = gcc_dir
 
 
-def SetMacXcodePath():
-  """Set DEVELOPER_DIR to the path to hermetic Xcode.app on Mac OS X."""
-  if sys.platform != 'darwin':
-    return
-
-  xcode_path = os.path.join(CHROMIUM_DIR, 'build', 'mac_files', 'Xcode.app')
-  if os.path.exists(xcode_path):
-    os.environ['DEVELOPER_DIR'] = xcode_path
-
-
 def VerifyVersionOfBuiltClangMatchesVERSION():
   """Checks that `clang --version` outputs RELEASE_VERSION. If this
   fails, update.RELEASE_VERSION is out-of-date and needs to be updated (possibly
@@ -413,10 +403,6 @@ def main():
   WriteStampFile('', STAMP_FILE)
   WriteStampFile('', FORCE_HEAD_REVISION_FILE)
 
-  # DEVELOPER_DIR needs to be set when Xcode isn't in a standard location
-  # and xcode-select wasn't run.
-  SetMacXcodePath()
-
   AddCMakeToPath(args)
   DeleteChromeToolsShim()