travis: remove unnecessary export PATH

This is done automatically by travis as part of the go setup.

.travis.yml

@@ -9,15 +9,17 @@ matrix:
     env: RACE=TRUE USE_LINT=FALSE
   - go: "1.10.x"
     env: RACE=FALSE USE_LINT=FALSE
+
 sudo: required
 install:
   - sudo add-apt-repository -y ppa:bitcoin/bitcoin -y
   - sudo apt-get update -q
   - sudo apt-get install bitcoind -y
   - export PATH=$PATH:$PWD/linux-amd64/
+
 script:
-  - export PATH=$PATH:$GOPATH/bin
   - make travis
+
 after_script:
   - echo "Uploading to termbin.com..." && find *.log | xargs -I{} sh -c "cat {} | nc termbin.com 9999 | xargs -r0 printf '{} uploaded to %s'"
   - echo "Uploading to file.io..." && tar -zcvO *.log | curl -s -F 'file=@-;filename=logs.tar.gz' https://file.io | xargs -r0 printf 'logs.tar.gz uploaded to %s\n'