fix headers path for android

lib/blockchain.py

@@ -65,7 +65,7 @@ blockchains = {}
 
 def read_blockchains(config):
     blockchains[0] = Blockchain(config, 0, None)
-    fdir = os.path.join(config.path, 'forks')
+    fdir = os.path.join(util.get_headers_dir(config), 'forks')
     if not os.path.exists(fdir):
         os.mkdir(fdir)
     l = filter(lambda x: x.startswith('fork_'), os.listdir(fdir))