travis: Check compile support for platform before build

`linux/riscv64` platform was added in `go 1.11` but compile was not
supported. Therefore buidling with `GOOS=linux GOARCH=riscv64` for `go
1.11` throws error.

This check handles above case.

Author: rayanimesh

.travis/complie_check.sh

@@ -5,6 +5,13 @@ dist_list=$(go tool dist list)
 for dist in ${dist_list}; do
     GOOS=$(echo ${dist} | cut  -d "/" -f 1)
     GOARCH=$(echo ${dist} | cut -d "/" -f 2)
+    set +e
+    GOOS=${GOOS} GOARCH=${GOARCH} go tool compile -V > /dev/null 2>&1 
+    if [[ $? -ne 0 ]]; then
+        echo "Compile support for ${GOOS}/${GOARCH} is not provided; skipping"
+        continue
+    fi
+    set -e
     echo "Building  ${GOOS}/${GOARCH}"
     GOOS=${GOOS} GOARCH=${GOARCH} go build  -o /dev/null
  done