Add llndk_stubs property

Prepare for making the relationship between an llndk_library stubs
module and the cc_library implementation module explicit by
adding an llndk_stubs property.  Each cc_library will be updated
to point to its llndk_library, and the llndk_library name will
be changed to make the .llndk suffix explicit.  Then the implicit
connection and suffix can be removed.

Bug: 170784825
Test: m checkbuild
Change-Id: I6b0482a3f286ec29b2e928551aa4317749f2b499

sysprop/sysprop_test.go

@@ -268,6 +268,7 @@ func TestSyspropLibrary(t *testing.T) {
 			system_shared_libs: [],
 			recovery_available: true,
 			host_supported: true,
+			llndk_stubs: "liblog.llndk",
 		}
 
 		cc_binary_host {
@@ -276,7 +277,7 @@ func TestSyspropLibrary(t *testing.T) {
 		}
 
 		llndk_library {
-			name: "liblog",
+			name: "liblog.llndk",
 			symbol_file: "",
 		}