libSceAppContent: Use last 16 characters of DLC folder to determine entitlement label (#3375)

* Use last 16 characters of DLC folder name to determine entitlement label

Code comments and commit name say it all.

* Clang

* Adjust comment

ftpdump appends -ac at the end of the entitlement label, so my comment was partially incorrect.

src/core/libraries/app_content/app_content.cpp

@@ -260,7 +260,12 @@ int PS4_SYSV_ABI sceAppContentInitialize(const OrbisAppContentInitParam* initPar
             auto entitlement_label = entry.path().filename().string();
             auto& info = addcont_info[addcont_count++];
             info.status = OrbisAppContentAddcontDownloadStatus::Installed;
-            entitlement_label.copy(info.entitlement_label, sizeof(info.entitlement_label));
+
+            // Our recommended dumping method prepends the folder name with the game serial
+            // Since they end the folder name with the entitlement label, copy from the end instead.
+            entitlement_label.copy(info.entitlement_label, sizeof(info.entitlement_label),
+                                   entitlement_label.length() -
+                                       ORBIS_NP_UNIFIED_ENTITLEMENT_LABEL_SIZE + 1);
         }
     }