Fix build error

.travis.yml

@@ -5,7 +5,7 @@ install:
   - export GOPATH=$HOME/gopath
   - export CGO_CPPFLAGS="-I$GOPATH/src/github.com/harmony-one/bls/include -I$GOPATH/src/github.com/harmony-one/mcl/include"
   - export CGO_LDFLAGS="-L$GOPATH/src/github.com/harmony-one/bls/lib -L$GOPATH/src/github.com/harmony-one/mcl/lib"
-  - export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$GOPATH/src/github.com/harmony-one/bls/lib
+  - export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$GOPATH/src/github.com/harmony-one/bls/lib:$GOPATH/src/github.com/harmony-one/mcl/lib
   - cd $HOME/gopath/src
   - cd github.com/harmony-one
   - git clone https://github.com/harmony-one/mcl.git

test/crypto/bls/main.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-   "fmt"
    "github.com/harmony-one/bls/ffi/go/bls"
    "log"
    "time"