Fix bug 131727 "compiler warnings in nsDiskCacheBlockFile.cpp" r=sdagley,

sr=darin.

netwerk/cache/src/nsDiskCacheBlockFile.cpp

@@ -36,7 +36,6 @@
 nsresult
 nsDiskCacheBlockFile::Open( nsILocalFile *  blockFile, PRUint32  blockSize)
 {
-    PRStatus  err = PR_SUCCESS;
     PRInt32   fileSize;
 
     mBlockSize = blockSize;

netwerk/cache/src/nsDiskCacheBlockFile.h

@@ -27,8 +27,7 @@
 #include "nsILocalFile.h"
 #include "nspr.h"
 
-enum { kBitMapBytes = 4096 };
-
+const unsigned short kBitMapBytes = 4096;
 
 /******************************************************************************
  *  nsDiskCacheBlockFile