problem with build gocrack

i have problems when build gocrack:
```
go build -tags """" -o builds/linux/amd64/gocrack_worker -ldflags \
"-X github.com/fireeye/gocrack/worker.CompileRev=e3b20e4 \
-X github.com/fireeye/gocrack/worker.CompileTime=1569172867 \
-X github.com/fireeye/gocrack/worker/engines/hashcat.HashcatVersion=" \
cmd/gocrack_worker/*.go
# github.com/fireeye/gocat
../gocat/gocat.go:239:7: could not determine kind of name for C.EVENT_OPENCL_SESSION_POST
../gocat/gocat.go:237:7: could not determine kind of name for C.EVENT_OPENCL_SESSION_PRE
Makefile:14: recipe for target 'build' failed
make: *** [build] Error 2
```

Start with the Makefile build target and the reported go build command, then inspect ../gocat/gocat.go around lines 237-239 where the C.EVENT_OPENCL_SESSION_PRE and C.EVENT_OPENCL_SESSION_POST names fail to resolve. Reproduce the build error and trace how those names are defined or referenced. Done means the documented build command completes successfully.

Written by the indexing model from the issue text.