Add win_xfa_clang trybot

infra/config/cq.cfg

 # See http://luci-config.appspot.com/schemas/projects/refs:cq.cfg for the
 # documentation of this file format.
 
 version: 1
 cq_name: "pdfium"
 git_repo_url: "https://pdfium.googlesource.com/pdfium.git"
 cq_status_url: "https://chromium-cq-status.appspot.com"
 
 rietveld {
   url: "https://codereview.chromium.org"
 }
 
 verifiers {
   reviewer_lgtm {
      committer_list: "project-pdfium-committers"
   }
 
   tree_status {
     tree_status_url: "https://pdfium-status.appspot.com"
   }
 
   try_job {
     buckets {
       name: "master.tryserver.client.pdfium"
       builders {
         name: "linux"
       }
       builders {
-        name: "linux_xfa"
-      }
-      builders {
         name: "linux_no_v8"
       }
       builders {
         name: "linux_skia"
         experiment_percentage: 100
       }
       builders {
+        name: "linux_xfa"
+      }
+      builders {
+        name: "linux_xfa_rel_gn"
+      }
+      builders {
         name: "mac"
       }
       builders {
-        name: "mac_xfa"
-      }
-      builders {
         name: "mac_no_v8"
       }
       builders {
         name: "mac_skia"
         experiment_percentage: 100
       }
       builders {
+        name: "mac_xfa"
+      }
+      builders {
+        name: "mac_xfa_rel_gn"
+      }
+      builders {
         name: "win"
       }
       builders {
-        name: "win_xfa"
-      }
-      builders {
         name: "win_no_v8"
       }
       builders {
         name: "win_skia"
         experiment_percentage: 100
       }
       builders {
-        name: "linux_xfa_rel_gn"
+        name: "win_xfa"
       }
       builders {
-        name: "mac_xfa_rel_gn"
+        name: "win_xfa_clang"
       }
       builders {
         name: "win_xfa_64_rel_gn"
       }
     }
   }
 }