Update the block file counter in database when using -reindex

This problem is like earth (mostly harmless). After/during a
-reindex, it means the statistics about the last block file
reported in debug.log are always of blk00000.dat instead of the
last file. Apart from that, it means a few more database entries
need to be read when finding a file to append to the first time.

src/main.cpp

@@ -1897,6 +1897,7 @@ bool FindBlockPos(CDiskBlockPos &pos, unsigned int nAddSize, unsigned int nHeigh
             nLastBlockFile = pos.nFile;
             infoLastBlockFile.SetNull();
             pblocktree->ReadBlockFileInfo(nLastBlockFile, infoLastBlockFile);
+            fUpdatedLast = true;
         }
     } else {
         while (infoLastBlockFile.nSize + nAddSize >= MAX_BLOCKFILE_SIZE) {