Fixed remaining quoting issues.
Fixed remaining quoting issues.

`CONFIGURE_FLAGS` might be multiple arguments so a passed string
should always be exploded when used. Conversely, `SRCDIR` can only be
used as a single argument; we do know that it does not contain spaces,
but should quote it nevertheless for consistency.

Review: https://reviews.apache.org/r/51603/

craimbert/mesos,yuquanshan/customizedMesos,gsantovena/mesos,andschwa/mesos,Aman-Jain-14/customizedMesos,gsantovena/mesos,abudnik/mesos,Gilbert88/mesos,Aman-Jain-14/customizedMesos,neilconway/mesos,zmalik/mesos,kaysoky/mesos,kaysoky/mesos,verizonlabs/mesos,dforsyth/mesos,gsantovena/mesos,reneploetz/mesos,dforsyth/mesos,abudnik/mesos,Gilbert88/mesos,gsantovena/mesos,neilconway/mesos,reneploetz/mesos,craimbert/mesos,verizonlabs/mesos,dforsyth/mesos,asamerh4/mesos,verizonlabs/mesos,dforsyth/mesos,gsantovena/mesos,andschwa/mesos,zmalik/mesos,yuquanshan/customizedMesos,verizonlabs/mesos,chhsia0/mesos,abudnik/mesos,Aman-Jain-14/customizedMesos,verizonlabs/mesos,zmalik/mesos,Aman-Jain-14/customizedMesos,zmalik/mesos,kaysoky/mesos,dforsyth/mesos,jpeach/mesos,Gilbert88/mesos,verizonlabs/mesos,chhsia0/mesos,gsantovena/mesos,gsantovena/mesos,yuquanshan/customizedMesos,Gilbert88/mesos,chhsia0/mesos,dforsyth/mesos,andschwa/mesos,Gilbert88/mesos,Aman-Jain-14/customizedMesos,dforsyth/mesos,chhsia0/mesos,andschwa/mesos,neilconway/mesos,kaysoky/mesos,neilconway/mesos,yuquanshan/customizedMesos,zmalik/mesos,yuquanshan/customizedMesos,chhsia0/mesos,asamerh4/mesos,jpeach/mesos,zmalik/mesos,andschwa/mesos,verizonlabs/mesos,yuquanshan/customizedMesos,andschwa/mesos,Gilbert88/mesos,neilconway/mesos,jpeach/mesos,jpeach/mesos,craimbert/mesos,jpeach/mesos,kaysoky/mesos,abudnik/mesos,Aman-Jain-14/customizedMesos,asamerh4/mesos,kaysoky/mesos,asamerh4/mesos,yuquanshan/customizedMesos,Gilbert88/mesos,chhsia0/mesos,asamerh4/mesos,zmalik/mesos,reneploetz/mesos,abudnik/mesos,abudnik/mesos,chhsia0/mesos,jpeach/mesos,andschwa/mesos,reneploetz/mesos,craimbert/mesos,reneploetz/mesos,reneploetz/mesos,craimbert/mesos,craimbert/mesos,asamerh4/mesos,jpeach/mesos,reneploetz/mesos,abudnik/mesos,asamerh4/mesos,neilconway/mesos,craimbert/mesos,neilconway/mesos,Aman-Jain-14/customizedMesos,kaysoky/mesos