Fix debug helper to work in static func

indra/llfilesystem/lldiskcache.cpp

@@ -139,6 +139,7 @@ void LLDiskCache::purge()
     }
 }
 
+//static
 const std::string LLDiskCache::assetTypeToString(LLAssetType::EType at)
 {
     /**
@@ -146,7 +147,7 @@ const std::string LLDiskCache::assetTypeToString(LLAssetType::EType at)
      * for inline initialization of an std::map<>
      */
     typedef std::map<LLAssetType::EType, std::string> asset_type_to_name_t;
-    asset_type_to_name_t asset_type_to_name =
+    static asset_type_to_name_t asset_type_to_name =
     {
         { LLAssetType::AT_TEXTURE, "TEXTURE" },
         { LLAssetType::AT_SOUND, "SOUND" },

indra/llfilesystem/lldiskcache.h

@@ -137,7 +137,7 @@ class LLDiskCache :
          * Utility function to convert an LLAssetType enum into a
          * string that we use as part of the cache file filename
          */
-        const std::string assetTypeToString(LLAssetType::EType at);
+        static const std::string assetTypeToString(LLAssetType::EType at);
 
         /**
          * Utility function to create the cache directory structure