inserting missing comma when adding '-ccbin' to direct argument flags

betatim provided a fix to Theano/Theano#1912 in commit Theano/Theano@bb4b1a5
however that fix did not include a comma on the end of the line, causing the
'-ccflags' to be merged with the next string '--fmad'
Merge pull request #1937 from matttrent/ccbin-argument-fix

inserting missing comma when adding '-ccbin' to direct argument flags