imlibsetroot: adapt to Imlib2 v1.7.5

imlib2-config is gone

imlibsetroot.c license header is actually MIT-advertising

pkgs/applications/graphics/imlibsetroot/default.nix

···
   };
 
   buildInputs = [ libX11 imlib2 libXinerama ];
+
   buildPhase = ''
-    gcc -g imlibsetroot.c -o imlibsetroot             \
-      `imlib2-config --cflags` `imlib2-config --libs` \
-      -I/include/X11/extensions -lXinerama -lX11
+    runHook preBuild
+
+    gcc -g imlibsetroot.c -o imlibsetroot              \
+      -I${imlib2.dev}/include -L${imlib2}/lib -lImlib2 \
+      -I${libX11.dev}/include -lXinerama -lX11
+
+    runHook postBuild
   '';
+
   installPhase = ''
-    mkdir -p $out/bin
-    install -m 755 imlibsetroot $out/bin
+    runHook preInstall
+    install -D -m 0755 imlibsetroot -t $out/bin
+    runHook postInstall
   '';
 
   meta = with lib; {
     description = "A Xinerama Aware Background Changer";
     homepage = "http://robotmonkeys.net/2010/03/30/imlibsetroot/";
-    license = licenses.gpl2;
+    license = licenses.mitAdvertising;
     platforms = platforms.linux;
     maintainers = with maintainers; [ dwarfmaster ];
   };