Make genrule portable for windows (#9889)

* Make genrule portable for windows

Using this does remove a user dependency on a bash under windows

* Use portable genrule for zlib dependency

protobuf.bzl

@@ -477,10 +477,12 @@ def internal_copied_filegroup(name, srcs, strip_prefix, dest, **kwargs):
         name = name + "_genrule",
         srcs = srcs,
         outs = outs,
-        cmd = " && ".join(
+        cmd_bash = " && ".join(
             ["cp $(location %s) $(location %s)" %
-             (s, _RelativeOutputPath(s, strip_prefix, dest)) for s in srcs],
-        ),
+             (s, _RelativeOutputPath(s, strip_prefix, dest)) for s in srcs]),
+        cmd_bat = " && ".join(
+            ["@copy /Y $(location %s) $(location %s) >NUL" %
+             (s, _RelativeOutputPath(s, strip_prefix, dest)) for s in srcs]),
     )
 
     native.filegroup(

third_party/zlib.BUILD

@@ -27,7 +27,11 @@ genrule(
     name = "copy_public_headers",
     srcs = _ZLIB_HEADERS,
     outs = _ZLIB_PREFIXED_HEADERS,
-    cmd = "cp $(SRCS) $(@D)/zlib/include/",
+    cmd_bash = "cp $(SRCS) $(@D)/zlib/include/",
+    cmd_bat = " && ".join(
+        ["@copy /Y $(location %s) $(@D)\\zlib\\include\\  >NUL" %
+         s for s in _ZLIB_HEADERS],
+    ),
 )
 
 cc_library(