Handle non-exist permission group correctly for pm list permissions

Test: adb shell pm list permissions non-exist-permission-group

Change-Id: I4e1a36ec673c9b3cc813346f6fce79f5017a099a
Signed-off-by: utzcoz <utzcoz@gmail.com>

services/core/java/com/android/server/pm/PackageManagerShellCommand.java

@@ -3516,7 +3516,7 @@ class PackageManagerShellCommand extends ShellCommand {
             }
             List<PermissionInfo> ps = mPermissionManager
                     .queryPermissionsByGroup(groupList.get(i), 0 /*flags*/);
-            final int count = ps.size();
+            final int count = (ps == null ? 0 : ps.size());
             boolean first = true;
             for (int p = 0 ; p < count ; p++) {
                 PermissionInfo pi = ps.get(p);