framework is not available to APEXes

The modules 'framework', 'framework-minus-apex', 'framework-all' contain
private symbols that shouldn't be accessible to Mainline modules.
Restrict the access by making the framework modules to be accessible
only to the platform (the non updatable part).

Bug: 145796956
Test: m
Change-Id: I08cb61a67aef88ffe04ef52670144e1cbeff3cf9

Android.bp

@@ -445,6 +445,7 @@ java_library {
     ],
     // For backwards compatibility.
     stem: "framework",
+    apex_available: ["//apex_available:platform"],
 }
 
 // This "framework" module is NOT installed to the device. It's
@@ -465,6 +466,7 @@ java_library {
         // TODO(jiyong): add stubs for APEXes here
     ],
     sdk_version: "core_platform",
+    apex_available: ["//apex_available:platform"],
 }
 
 java_library {
@@ -473,7 +475,8 @@ java_library {
     srcs: [":framework-all-sources"],
     installable: false,
     libs: ["app-compat-annotations"],
-    static_libs: ["exoplayer2-core"]
+    static_libs: ["exoplayer2-core"],
+    apex_available: ["//apex_available:platform"],
 }
 
 java_library {