Attempt to fix #22628 by killing all stdtests

Author: brson

master/master.cfg

@@ -907,6 +907,16 @@ def make_and_check_buildfactory(check, android, windows, parallel):
                       workdir=BUILD_WORKDIR,
                       command=[MakeCommand(), "clean-llvm"]))
 
+    if windows:
+        taskkill_cmd = ["taskkill", "/T", "/F", "/FI", "IMAGENAME eq stdtest*"]
+        # FIXME https://github.com/rust-lang/rust/issues/22628
+        # Windows test hangs cause lots of problems. This tries
+        # to kill stdtest.
+        f.addStep(ShellCommand(env=CommandEnv(),
+                               name="taskkill hack",
+                               command=taskkill_cmd,
+                               workdir=WORKDIR))
+
     # msys make is pretty buggy with paralellization
     if windows or not parallel:
         command = [MakeCommand()]