Support cc_library as LLNDK without llndk_library

Allow cc_library modules to configure themselves as an LLNDK library
using llndk.symbol_file instead of llndk_stubs pointing to an
llndk_library module.

Bug: 170784825
Test: TestEmbeddedLlndkLibrary
Change-Id: Id884cdada7094bbea6809a98e687e039778c5dc6

cc/cc.go

@@ -1145,12 +1145,7 @@ func (m *Module) HasLlndkStubs() bool {
 func (c *Module) isImplementationForLLNDKPublic() bool {
 	library, _ := c.library.(*libraryDecorator)
 	return library != nil && library.hasLLNDKStubs() &&
-		(!Bool(library.Properties.Llndk.Private) ||
-			// TODO(b/170784825): until the LLNDK properties are moved into the cc_library,
-			// the non-Vendor variants of the cc_library don't know if the corresponding
-			// llndk_library set private: true.  Since libft2 is the only private LLNDK
-			// library, hardcode it during the transition.
-			c.BaseModuleName() != "libft2")
+		!Bool(library.Properties.Llndk.Private)
 }
 
 // Returns true for LLNDK-private, VNDK-SP-private, and VNDK-core-private.