treewide: Start to break up static overlay

We can use use `stdenv.hostPlatform.isStatic` instead, and move the
logic per package. The least opionated benefit of this is that it makes
it much easier to replace packages with modified ones, as there is no
longer any issue of overlay order.

CC @FRidh @matthewbauer

pkgs/development/libraries/audiofile/default.nix

@@ -38,7 +38,7 @@ stdenv.mkDerivation rec {
   #
   # There might be a more sensible way to do this with autotools, but I am not
   # smart enough to discover it.
-  preBuild = lib.optionalString stdenv.targetPlatform.isStatic ''
+  preBuild = lib.optionalString stdenv.hostPlatform.isStatic ''
     make -C libaudiofile $makeFlags
     sed -i "s/dependency_libs=.*/dependency_libs=' -lstdc++'/" libaudiofile/libaudiofile.la
   '';