Fix #38 cannot load such file crcx

[rocLv]

Due to rake bug (or api change), rake failed when trying to compile gem extensions.

[CLAassistant]

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[coveralls]

Coverage remained the same at 98.01% when pulling edce7b6 on rocLv:master into 4091324 on aliyun:master.

[mars-coder]

Thanks for your pr!

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2. Could you tell us something abort environment that the bug occurred? (Windows? MacOS? Linux? )