Clang build scripts: LLVM 'master' is now 'main'

See http://lists.llvm.org/pipermail/llvm-dev/2020-December/147175.html

Bug: none
Change-Id: Ifd6abe11b833961d9ff25bdd6e9d3315523cd95f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2577360Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Hans Wennborg <hans@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834214}

tools/clang/scripts/build.py

@@ -165,8 +165,9 @@ def UrlOpen(url):
 
 def GetLatestLLVMCommit():
   """Get the latest commit hash in the LLVM monorepo."""
-  ref = json.loads(UrlOpen(('https://api.github.com/repos/'
-                            'llvm/llvm-project/git/refs/heads/master')))
+  ref = json.loads(
+      UrlOpen(('https://api.github.com/repos/'
+               'llvm/llvm-project/git/refs/heads/main')))
   assert ref['object']['type'] == 'commit'
   return ref['object']['sha']
 

tools/clang/scripts/build_clang_tools_extra.py

@@ -50,7 +50,7 @@ def FetchLLVM(checkout_dir, revision):
   except subprocess.CalledProcessError:
     # Otherwise, try to update it.
     print('-- Attempting to update existing repo')
-    args = ['git', 'pull', '--rebase', 'origin', 'master']
+    args = ['git', 'pull', '--rebase', 'origin', 'main']
     subprocess.check_call(args, cwd=checkout_dir, shell=sys.platform == 'win32')
   if revision:
     args = ['git', 'checkout', revision]