Actual version of libjackasyn is very old, with the latest version, compilation works. I have use the libjackasyn-0.10.ebuild, renamed it libjackasyn-0.13.ebuild with a new source url SRC_URI="http://gige.xdv.org/soft/libjackasyn/download/${P}.tar.gz" and i have deleted the line "epatch ....".
config.status: creating Makefile config.status: creating jacklaunch cc -O2 -Wall -I. -fPIC -rdynamic -DMAJOR=0 -DMINOR=10 -c -o libjackasyn.o libjackasyn.c libjackasyn.c: In function 'jack_bufsize': libjackasyn.c:278: warning: format '%lu' expects type 'long unsigned int', but argument 2 has type 'jack_nframes_t' cc -O2 -Wall -I. -fPIC -rdynamic -DMAJOR=0 -DMINOR=10 -c -o libjackoss.o libjackoss.c libjackoss.c: In function 'jackoss_write': libjackoss.c:366: warning: format '%d' expects type 'int', but argument 5 has type 'size_t' gcc -c -O2 -Wall -I. -fPIC -rdynamic -DMAJOR=0 -DMINOR=10 -DLD_PRELOAD -o libjackoss_pl.o libjackoss.c libjackoss.c: In function 'write': libjackoss.c:366: warning: format '%d' expects type 'int', but argument 5 has type 'size_t' libjackoss.c: At top level: libjackoss.c:631: error: '__fcntl' aliased to undefined symbol 'fcntl' libjackoss.c:640: error: '_fcntl' aliased to undefined symbol 'fcntl' make: *** [libjackoss_pl.o] Error 1 !!! ERROR: media-libs/libjackasyn-0.10 failed. will test 0.13
devel.demudi.org seems down, unable to fetch from upstream
Bumped that one some days ago