gx: remove support

Author: Stebalien

.travis.yml

@@ -4,14 +4,13 @@ os:
 language: go
 
 go:
-  - 1.11.x
+  - 1.12.x
 
 env:
   global:
     - GOTFLAGS="-race"
     - IPFS_REUSEPORT=false
   matrix:
-    - BUILD_DEPTYPE=gx
     - BUILD_DEPTYPE=gomod
 
 
@@ -25,7 +24,6 @@ script:
 
 cache:
   directories:
-    - $GOPATH/src/gx
     - $GOPATH/pkg/mod
     - /home/travis/.cache/go-build