posix: Update syntax for fixed-length array definition
posix: Update syntax for fixed-length array definition

The syntax for fixed-length arrays changed in commit 5843b781.
Fixes bug 590433.

themiwi/vala,tjol/vala-tjol,phako/vala,spidermonkdust/vala,kamanashisroy/aroop,jessevdk/vala,frida/vala,lovebug356/vala,severinh/vala,GNOME/vala,spidermonkdust/vala,phako/vala,GNOME/vala,playya/vala,themiwi/vala,playya/vala,tjol/vala-tjol,spidermonkdust/vala,frida/vala,flobrosch/vala-fixes,themiwi/vala,playya/vala,xdave/pvala,Jc2k/vala,rvu95/vala,jessevdk/vala,Distrotech/vala,rvu95/vala,kamanashisroy/aroop,Jc2k/vala,Distrotech/vala,frida/vala,Distrotech/vala,tjol/vala-tjol,GNOME/vala,frida/vala,frida/vala,GNOME/vala,lovebug356/vala,kamanashisroy/aroop,flobrosch/vala-fixes,jessevdk/vala,severinh/vala,severinh/vala,flobrosch/vala-fixes,rvu95/vala