Remove Mac try jobs from the CQ.

They're not working right now.

Bug: chromium:888687
Change-Id: I723a382d666e24c4f7f35c7b9369341b4bdebf1a
Reviewed-on: https://boringssl-review.googlesource.com/32124
Reviewed-by: Adam Langley <agl@google.com>

infra/config/cq.cfg

diff --git a/infra/config/cq.cfg b/infra/config/cq.cfg
index 72c95d8..b0d1f83 100644
--- a/infra/config/cq.cfg
+++ b/infra/config/cq.cfg
@@ -43,9 +43,10 @@
       builders { name: "linux_shared" }
       builders { name: "linux_small" }
 
-      builders { name: "mac" }
-      builders { name: "mac_rel" }
-      builders { name: "mac_small" }
+      # Mac builders are broken. https://crbug.com/888687.
+      # builders { name: "mac" }
+      # builders { name: "mac_rel" }
+      # builders { name: "mac_small" }
 
       builders { name: "win32" }
       builders { name: "win32_rel" }