Q1: Is this a big problem?
I don't know. Isn't the warning of the "informational" level? I mean, does it kill make? Weird I don't see no "-Wall" flag tho...
Q2: If yes or no, how can it be fixed.
: syntax error near unexpected token `fi'
To use "mkstemp" you would have to rewrite the code, but "msktemp" isn't equal to and doesn't work like "mktemp" in more than a few aspects. If disregarding the error works, well, then disregard it and fire off a message to the authors to clear up any doubts on mktemp vs mkstemp.