Compiler warning: ignoring return value of 'dup' declared with attribute 'warn_unused_result'

[ileanadumitrescu95]

During Debian build, there is a compiler warning:

gcc -DHAVE_CONFIG_H -I. -I..  -I.. -DLIBZVBI_CHAINS_PATH=\"libzvbi-chains.so.0\" -D_REENTRANT -D_GNU_SOURCE -Wdate-time -D_FORTIFY_SOURCE=2  -g -O2 -ffile-prefix-map=/build/zvbi-0.2.40=. -fstack-protector-strong -Wformat -Werror=format-security -c -o proxyd.o proxyd.c
proxyd.c: In function 'vbi_proxyd_init':
proxyd.c:2708:10: warning: ignoring return value of 'dup' declared with attribute 'warn_unused_result' [-Wunused-result]
 2708 |          dup(1);
      |          ^~~~~~

[ileanadumitrescu95]

Resolved in commit 40b7863