Remove USE_CACHE support, since we only need MC support.

BUG=6051742

This change also removes the legacy bcc_cache.h header by moving any relevant
defines still there to bcc_mccache.h. These types/values are now renamed to
generally use "MCO" instead of "OBCC".

Change-Id: I6c611bd296c0335cacd82025933f36eb55bff72f
diff --git a/lib/ExecutionEngine/Script.h b/lib/ExecutionEngine/Script.h
index f3e933d..16a453c 100644
--- a/lib/ExecutionEngine/Script.h
+++ b/lib/ExecutionEngine/Script.h
@@ -44,9 +44,7 @@
     enum StatusType {
       Unknown,
       Compiled,
-#if USE_CACHE
-      Cached,
-#endif
+      Cached
     };
   }
 
@@ -71,12 +69,9 @@
 
     union {
       ScriptCompiled *mCompiled;
-#if USE_CACHE
       ScriptCached *mCached;
-#endif
     };
 
-#if USE_CACHE
     std::string mCacheDir;
     std::string mCacheName;
 
@@ -87,7 +82,6 @@
     inline std::string getCacheInfoPath() const {
       return getCachedObjectPath().append(".info");
     }
-#endif
 
     bool mIsContextSlotNotAvail;
 
@@ -224,14 +218,13 @@
     }
 
   private:
-#if USE_CACHE
     //
     // It returns 0 if there's a cache hit.
     //
     // Side effect: it will set mCacheDir, mCacheName.
     int internalLoadCache(char const *cacheDir, char const *cacheName,
                           bool checkOnly);
-#endif
+
     int internalCompile(const CompilerOption&);
   };