watch: remove

This can be built in the procps-ng/default.nix expression.

pkgs/os-specific/linux/procps-ng/default.nix

@@ -13,7 +13,8 @@ stdenv.mkDerivation rec {
   buildInputs = [ ncurses ];
   nativeBuildInputs = [ pkgconfig ];
 
-  makeFlags = "usrbin_execdir=$(out)/bin";
+  makeFlags = [ "usrbin_execdir=$(out)/bin" ]
+    ++ lib.optionals stdenv.isDarwin [ "watch" "PKG_LDFLAGS="];
 
   enableParallelBuilding = true;
 
@@ -23,12 +24,17 @@ stdenv.mkDerivation rec {
     [ "ac_cv_func_malloc_0_nonnull=yes"
       "ac_cv_func_realloc_0_nonnull=yes" ];
 
+  installPhase = if stdenv.isDarwin then ''
+    install -m 0755 -D watch $out/bin/watch
+    install -m 0644 -D watch.1 $out/share/man/man1/watch.1
+  '' else null;
+
   meta = {
     homepage = https://gitlab.com/procps-ng/procps;
     description = "Utilities that give information about processes using the /proc filesystem";
     priority = 10; # less than coreutils, which also provides "kill" and "uptime"
     license = lib.licenses.gpl2;
-    platforms = lib.platforms.linux ++ lib.platforms.cygwin;
+    platforms = lib.platforms.linux ++ lib.platforms.cygwin ++ lib.platforms.darwin;
     maintainers = [ lib.maintainers.typetetris ];
   };
 }