Allow shared_relro to access PackageManager.

Allow the shared_relro creation process to make calls to PackageManager,
so that it can create a classloader corresponding to the current WebView
implementation. This avoids needing to pass an absolute path to the
native library to the process, which required that the calling code
duplicate existing logic in the framework to find the library and
resulted in bugs and inconsistencies.

Bug: 110790153
Test: WebView-related CTS and GTS tests
Change-Id: I9902bb0400e2a800021dac06278151c8541d458f

public/shared_relro.te

@@ -8,3 +8,4 @@ allow shared_relro shared_relro_file:file create_file_perms;
 # Needs to contact the "webviewupdate" and "activity" services
 allow shared_relro activity_service:service_manager find;
 allow shared_relro webviewupdate_service:service_manager find;
+allow shared_relro package_service:service_manager find;