I attach the log file with the second make.
Then I tried with your fix and again with your fix and the second
make. The result is the same.
/bin/sh: -c: riga 1: errore di sintassi vicino al token non atteso "("
is your /bin/sh actually bash or something else?
I don't know if it is important but right before the crash the
terminal stays a few seconds on the line:
touch /home/paz/cinelerra5/cinelerra-5.1/thirdparty/../thirdparty/build/fftw.built
In Arch x265 package is flagged "out-of-date"; This might say that
there is a new version but also that there is something wrong and they
need to work on it.