Check-in CIPD ninja.exe as a workaround

There are still some places that directly calls depot_tools/ninja{,.exe} without ensuring .cipd_bin dir.
This is a binary build on 3pp CIPD pipeline specified in cipd_manifest.txt.

Bug: 931218
Change-Id: I9f455bf47d648ce8e5bf74bd6c6d356867766314
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3708571
Auto-Submit: Junji Watanabe <jwata@google.com>
Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>

.gitignore

@@ -7,7 +7,9 @@
 /.versions
 
 # ignore ninja.exe copied from .cipd_bin.
-/ninja.exe
+# TODO(crbug.com/931218): checkin ninja.exe for issues that can't ensure
+# ninja.exe as expected.
+# /ninja.exe
 
 # Ignore "disable auto update" sentinel file.
 .disable_auto_update

cipd_bin_setup.bat

@@ -5,4 +5,5 @@
 
 call "%~dp0\cipd.bat" ensure -log-level warning -ensure-file "%~dp0\cipd_manifest.txt" -root "%~dp0\.cipd_bin"
 :: copy ninja.exe to the root since many places assume ninja.exe exists in depot_tools.
-copy /y "%~dp0\.cipd_bin\ninja.exe" "%~dp0\ninja.exe" > nul
+:: TODO(crbug.com/931218): check in ninja.exe for now.
+:: copy /y "%~dp0\.cipd_bin\ninja.exe" "%~dp0\ninja.exe" > nul