lsfd: fix bsearch macro usage with glibc C23

lsfd: fix bsearch macro usage with glibc C23

C23 requires bsearch to be a const preserving macro, build now fails
with

../lsfd-cmd/lsfd.c:1879:75: error: macro ‘bsearch’ passed 6 arguments, but takes just 5
 1879 |                                     nfds, sizeof(struct pollfd), pollfdcmp))
      |                                                                           ^
In file included from ../include/c.h:17,
                 from ../lsfd-cmd/lsfd.c:48:
/usr/include/stdlib.h:987:10: note: macro ‘bsearch’ defined here
  987 | # define bsearch(KEY, BASE, NMEMB, SIZE, COMPAR)                        \

  add parenthesis around expression to fix it.