Rename APEX file_contexts as <name>-file_context

It was <name>_file_context before. Changing for better readability.

Bug: 119034475
Test: m apex.test com.android.tzdata com.android.runtime
Change-Id: I0d3d3319370cdbb366d06626c8ac978ca8d875c3
diff --git a/apex/apex.go b/apex/apex.go
index 177856e..81e969d 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -570,7 +570,7 @@
 	manifest := android.PathForModuleSrc(ctx, proptools.StringDefault(a.properties.Manifest, "manifest.json"))
 
 	fcName := proptools.StringDefault(a.properties.File_contexts, a.ModuleBase.Name())
-	fileContextsPath := "system/sepolicy/apex/" + fcName + "_file_contexts"
+	fileContextsPath := "system/sepolicy/apex/" + fcName + "-file_contexts"
 	fileContextsOptionalPath := android.ExistentPathForSource(ctx, fileContextsPath)
 	if !fileContextsOptionalPath.Valid() {
 		ctx.ModuleErrorf("Cannot find file_contexts file: %q", fileContextsPath)