This is unnecessary since we are using AC_USE_SYSTEM_EXTENSIONS in
configure.ac, which makes the compiler always run with -D_GNU_SOURCE=1
when building for GNU/Linux.
Also, the #define _GNU_SOURCE in src/util.c, and in
src/inject_errors.c (--enable-inject-errors), were not guarded by a
#ifndef _GNU_SOURCE so they were just triggering redefinition warnings.
It has no effect after the change c4524da.
Bug reported by the clang static analyzer.
Description: Value stored to 'value' is never read
File: jq/src/util.c
Line: 439
Stop losing \0s from the end of files because we don't know how much
fgets() read into our buffer. If we prefill the buffer with anything
other than zeroes, we can actually tell the difference between the
terminator and unused space in the buffer.
This is possibly more expensive, but at least it should be correct.
Fixes#1504
Emanuele Torre