Switch VS2017 compile bots to Windows 10.

Per tandrii, these may work better.

Change-Id: I2719035d6f2a06b2baeb7fe820d77e64d0e9542b
Reviewed-on: https://boringssl-review.googlesource.com/29164
Reviewed-by: Andrii Shyshkalov <tandrii@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
diff --git a/cr-buildbucket.cfg b/cr-buildbucket.cfg
index 65e8cc8..8743824 100644
--- a/cr-buildbucket.cfg
+++ b/cr-buildbucket.cfg
@@ -215,29 +215,32 @@
       dimensions: "cpu:x86-64"
     }
 
-    # Add compile-only versions of our other supported toolchains.
+    # Add compile-only versions of our other supported toolchains. Use Windows
+    # 10 machines because there is more capacity available, and they are not
+    # affected by the E:\b\depot_tools issue of https://crbug.com/852609.
+    # (These are compile-only, so we don't care what OS they build on.)
     builders {
       category: "2win"
       name: "win32_vs2017_compile"
-      dimensions: "os:Windows-7-SP1"
+      dimensions: "os:Windows-10"
       dimensions: "cpu:x86-64"
     }
     builders {
       category: "2win"
       name: "win64_vs2017_compile"
-      dimensions: "os:Windows-7-SP1"
+      dimensions: "os:Windows-10"
       dimensions: "cpu:x86-64"
     }
     builders {
       category: "2win"
       name: "win32_clang_vs2017_compile"
-      dimensions: "os:Windows-7-SP1"
+      dimensions: "os:Windows-10"
       dimensions: "cpu:x86-64"
     }
     builders {
       category: "2win"
       name: "win64_clang_vs2017_compile"
-      dimensions: "os:Windows-7-SP1"
+      dimensions: "os:Windows-10"
       dimensions: "cpu:x86-64"
     }