Merge pull request #20 from philsc:not-compatible

PiperOrigin-RevId: 343286570
Change-Id: I1bb23135d8114c6189cc1d753b570da9416c505d

BUILD

@@ -13,3 +13,17 @@ filegroup(
         "//os:srcs",
     ],
 )
+
+# For use in Incompatible Target Skipping:
+# https://docs.bazel.build/versions/master/platforms.html#skipping-incompatible-targets
+#
+# Specifically this lets targets declare incompatibility with some set of
+# platforms. See
+# https://docs.bazel.build/versions/master/platforms.html#more-expressive-constraints
+# for some more details.
+constraint_setting(name = "incompatible_setting")
+
+constraint_value(
+    name = "incompatible",
+    constraint_setting = ":incompatible_setting",
+)