Don't run win dist builds on win slaves (only windist)

Author: alexcrichton

master/master.cfg

@@ -1621,7 +1621,7 @@ def platform_snap_slaves(p):
 # FIXME: The linux AMI instances are using valgrind 3.7 and we need 3.8+
 # This rule limits which bots we run the valgrinding dist snapshot on.
 def platform_dist_slaves(p):
-    if 'musl' in p or 'cross' in p or 'ios' in p:
+    if 'musl' in p or ('cross' in p and not 'win' in p) or 'ios' in p:
         return platform_slaves(p)
 
     # p is exactly the platform name, ie arm-android