Do not propagate dynamic dependencies for stub libs.

Test: m nothing
Test: Build an SDK snapshot including libc, check that the generated
  cc_prebuilt_library_shared for it is a stub that doesn't depend on
  ld-android.
Bug: 152255951
Bug: 154310674
Change-Id: Ie5ec02aebdf00b75756a6eda40db821488d30065

sdk/cc_sdk_test.go

@@ -1748,8 +1748,13 @@ func TestStubsLibrary(t *testing.T) {
 			native_shared_libs: ["stubslib"],
 		}
 
+		cc_library {
+			name: "internaldep",
+		}
+
 		cc_library {
 			name: "stubslib",
+			shared_libs: ["internaldep"],
 			stubs: {
 				symbol_file: "some/where/stubslib.map.txt",
 				versions: ["1", "2", "3"],