MIPS64: Add support for depot_tools on mips64.

BUG= 865294

R= tandrii@chromium.org

Change-Id: I8ad56887882b897d605dc92e0e61c17de0a74967
Reviewed-on: https://chromium-review.googlesource.com/1141563
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Robbie Iannucci <iannucci@chromium.org>
diff --git a/gclient.py b/gclient.py
index d9341a5..3d9d8a9 100755
--- a/gclient.py
+++ b/gclient.py
@@ -1185,6 +1185,7 @@
         'checkout_arm64': 'arm64' in self.target_cpu,
         'checkout_x86': 'x86' in self.target_cpu,
         'checkout_mips': 'mips' in self.target_cpu,
+        'checkout_mips64': 'mips64' in self.target_cpu,
         'checkout_ppc': 'ppc' in self.target_cpu,
         'checkout_s390': 's390' in self.target_cpu,
         'checkout_x64': 'x64' in self.target_cpu,