Move platform constraints to bazel_common_rules.

This enables sharing of platform constraints between platform and kernel builds.

Bug: 304594734

Test: treehugger
Change-Id: I48091eeaf2e529c3f180ba056da3935911868b14
diff --git a/cc/bp2build.go b/cc/bp2build.go
index ec5d522..57333b8 100644
--- a/cc/bp2build.go
+++ b/cc/bp2build.go
@@ -1514,7 +1514,7 @@
 		Constraint_values: bazel.MakeLabelListAttribute(
 			bazel.MakeLabelList(
 				[]bazel.Label{
-					bazel.Label{Label: "//build/bazel/platforms/os:android"},
+					bazel.Label{Label: "//build/bazel_common_rules/platforms/os:android"},
 				},
 			),
 		),