treewide: strip more things in cross

Stripping reduces closure sizes.

pkgs/development/libraries/libpcap/default.nix

@@ -22,12 +22,14 @@ stdenv.mkDerivation rec {
     "ac_cv_linux_vers=2"
   ];
 
-  dontStrip = stdenv.hostPlatform != stdenv.buildPlatform;
-
   prePatch = stdenv.lib.optionalString stdenv.isDarwin ''
     substituteInPlace configure --replace " -arch i386" ""
   '';
 
+  postInstall = ''
+    rm -f $out/lib/libpcap.a
+  '';
+
   meta = with stdenv.lib; {
     homepage = "https://www.tcpdump.org";
     description = "Packet Capture Library";

pkgs/development/libraries/readline/6.3.nix

@@ -32,10 +32,6 @@ stdenv.mkDerivation {
      in
        import ./readline-6.3-patches.nix patch);
 
-  # Don't run the native `strip' when cross-compiling.
-  dontStrip = stdenv.hostPlatform != stdenv.buildPlatform;
-  bash_cv_func_sigsetjmp = if stdenv.isCygwin then "missing" else null;
-
   meta = with stdenv.lib; {
     description = "Library for interactive line editing";
 

pkgs/development/libraries/readline/7.0.nix

@@ -32,10 +32,6 @@ stdenv.mkDerivation rec {
     ]
     ++ upstreamPatches;
 
-  # Don't run the native `strip' when cross-compiling.
-  dontStrip = stdenv.hostPlatform != stdenv.buildPlatform;
-  bash_cv_func_sigsetjmp = if stdenv.isCygwin then "missing" else null;
-
   meta = with stdenv.lib; {
     description = "Library for interactive line editing";
 

pkgs/development/libraries/readline/8.0.nix

@@ -32,10 +32,6 @@ stdenv.mkDerivation rec {
     ]
     ++ upstreamPatches;
 
-  # Don't run the native `strip' when cross-compiling.
-  dontStrip = stdenv.hostPlatform != stdenv.buildPlatform;
-  bash_cv_func_sigsetjmp = if stdenv.isCygwin then "missing" else null;
-
   meta = with stdenv.lib; {
     description = "Library for interactive line editing";
 

pkgs/development/tools/misc/libtool/libtool2.nix

@@ -26,10 +26,6 @@ stdenv.mkDerivation rec {
 
   enableParallelBuilding = true;
 
-  # Don't run the native `strip' when cross-compiling.  This breaks at least
-  # with `.a' files for MinGW.
-  dontStrip = stdenv.hostPlatform != stdenv.buildPlatform;
-
   meta = with stdenv.lib; {
     description = "GNU Libtool, a generic library support script";
     longDescription = ''