termcap: fix build with gcc15

The ISO C23, which is the default in GCC 15, changes the meaning of an
empty argument list from an unspecified list to no arguments, thus
breaking the build.

This is fixed by switching the language standard to `gnu89` (dialect of
ISO C90).

pkgs/by-name/te/termcap/package.nix

@@ -8,12 +8,12 @@
   enableShared ? !stdenv.hostPlatform.isStatic,
 }:
 
-stdenv.mkDerivation rec {
+stdenv.mkDerivation (finalAttrs: {
   pname = "termcap";
   version = "1.3.1";
 
   src = fetchurl {
-    url = "mirror://gnu/termcap/termcap-${version}.tar.gz";
+    url = "mirror://gnu/termcap/termcap-${finalAttrs.version}.tar.gz";
     hash = "sha256-kaDiLlOHykRntbyxjt8cUbkwJi/UZtX9o5bdnSZxkQA=";
   };
 
@@ -43,6 +43,7 @@ stdenv.mkDerivation rec {
   env.NIX_CFLAGS_COMPILE = toString (
     [
       "-DSTDC_HEADERS"
+      "-std=gnu89"
     ]
     ++ lib.optionals stdenv.cc.isClang [
       "-Wno-implicit-function-declaration"
@@ -76,4 +77,4 @@ stdenv.mkDerivation rec {
     maintainers = with lib.maintainers; [ wegank ];
     platforms = lib.platforms.all;
   };
-}
+})