Without manual override following problematic code in generated
"configure" script (line 15918):

case "$host_os" in
# Guess yes on glibc systems.
-gnu | gnu*) gl_cv_func_signbit="guessing yes" ;;
# Guess yes on native Windows.
mingw*) gl_cv_func_signbit="guessing yes" ;;
# If we don't know, assume the worst.
*) gl_cv_func_signbit="guessing no" ;;
esac

results in declaration conflict with gnulib declaring

int signbit(double)

while system "math.h" providing modern declaration as

constexpr bool signbit(double)

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.