mac: Switch to Xcode 12.0.1 stable

Xcode 12.0.1 still ships with the macOS 10.15 SDK, so this
doesn't bump the SDK version yet.

However, some of the binaries in Xcode 12.0.1 need 10.15 to run
(namely, bison gm4 gperf) while the others need 10.14.6, so this
is still a good exercise to make sure that all our bots can handle
10.15+ binaries now (which is a prerequisite to switching to Xcode
12.2 / the 11.0 SDK once it's out of beta).

I temporarily locally removed the libcodedirectory.dylib line
from xcode_binaries.yaml while uploading the 12.0.1 cipd package,
since 12.0.1 doesn't contain that file yet.

Bug: 1108831
Change-Id: I542e859ae3d245f3715efd1f5b8e7cc5d806790f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2465807Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816721}

build/mac_toolchain.py

@@ -31,9 +31,9 @@ import sys
 # To build these packages, see comments in build/xcode_binaries.yaml
 MAC_BINARIES_LABEL = 'infra_internal/ios/xcode/xcode_binaries/mac-amd64'
 MAC_BINARIES_TAG = {
-    # This contains binaries from Xcode 11.2.1, along with the 10.15 SDKs (aka
-    # 11B53).
-    'default': 'wXywrnOhzFxwLYlwO62UzRxVCjnu6DoSI2D2jrCd00gC',
+    # This contains binaries from Xcode 12.0.1, along with the 10.15 SDK (aka
+    # 12A7300).
+    'default': '89j_tSMJj0_9hMbceEg-P-VmiY_4CeYwsPE1e_zzRPcC',
     # This contains binaries from Xcode 12.2 beta 2, along with the
     # 11 SDK (aka 12B5025f).
     'xcode_12_beta': 'G4U9cOycs9JFzxLNSMaRuoS3NZwiB6RLwg0v4dh3Vw4C',