gnumake: Drop pkgconfig if not building with guileSupport

This used to be the case before commit 531e4b80c97002 which seems to
have dropped it by accident.

Removes one unnecessary build of pkgconfig during stdenv bootstrapping.

Changed files
+1 -1
pkgs
development
tools
build-managers
gnumake
+1 -1
pkgs/development/tools/build-managers/gnumake/4.2/default.nix
···
./pselect.patch
];
-
nativeBuildInputs = [ pkgconfig ];
+
nativeBuildInputs = stdenv.lib.optionals guileSupport [ pkgconfig ];
buildInputs = stdenv.lib.optionals guileSupport [ guile ];
configureFlags = stdenv.lib.optional guileSupport "--with-guile";