Abstract prebuilt_etc into prebuilt_file

Bug: 215723302
Test: bp2build.sh
Test: mixed_{libc,droid}.sh
Change-Id: I0dab7a6209320e31cfdfe1ce28cacd4f37c11024
diff --git a/etc/prebuilt_etc.go b/etc/prebuilt_etc.go
index a142833..aa4b889 100644
--- a/etc/prebuilt_etc.go
+++ b/etc/prebuilt_etc.go
@@ -723,8 +723,8 @@
 	}
 
 	props := bazel.BazelTargetModuleProperties{
-		Rule_class:        "prebuilt_etc",
-		Bzl_load_location: "//build/bazel/rules:prebuilt_etc.bzl",
+		Rule_class:        "prebuilt_file",
+		Bzl_load_location: "//build/bazel/rules:prebuilt_file.bzl",
 	}
 
 	ctx.CreateBazelTargetModule(props, android.CommonAttributes{Name: module.Name()}, attrs)