fix(build): fix variable in build script

[gitoso]

What is the purpose of the change

The line unzip -o ${fname_libevent} >unziplibevent.txt 2>& creates the file unziplibevent.txt in the directory. So when setting the directory name with libevent_dir=$(ls | grep libevent | grep .*[^zip]$) the variable will have the name of two files and cd ${libevent_dir} will prompt cd: Too many arguments.

Brief changelog

Just adding the .txt extension to the exclusion list during the grep command is enough to solve the problem. In the end we have libevent_dir=$(ls | grep libevent | grep .*[^zip^txt]$).

[ShannonDing]

hello, @gitoso , welcome to apache rocketmq community, the GSoC 2020 will be starting soon, could you please send an email to me and I will send you some information about it if you are interested in it?

[gitoso]

hello, @gitoso , welcome to apache rocketmq community, the GSoC 2020 will be starting soon, could you please send an email to me and I will send you some information about it if you are interested in it?

Thank you, I sent a message to the email in your github profile ^^

[vongosling]

@gitoso here are some preliminary proposal(apache/rocketmq-externals#512). if you are interested, we would like to help you to complete these in the nearing GSoC 2020.