libelf: Fix cross compilation

There is an upstream bug where it is assumed that if host != build, host
doesn't support shared libraries. We override that overly conservative
check. See
http://lists.uclibc.org/pipermail/uclibc-cvs/2005-August/019383.html

Also clean up some comments.

pkgs/development/libraries/libelf/default.nix

@@ -1,5 +1,5 @@
-{ stdenv, fetchurl
+{ stdenv
-, gettext, glibc
+, fetchurl, autoreconfHook, gettext
 , buildPlatform, hostPlatform
 }:
 
@@ -17,12 +17,20 @@ stdenv.mkDerivation rec {
 
   doCheck = true;
 
-  # Libelf's custom NLS macros fail to determine the catalog file extension on
+  configureFlags = []
-  # Darwin, so disable NLS for now.
+       # Configure check for dynamic lib support is broken, see
-  # FIXME: Eventually make Gettext a build input on all platforms.
+       # http://lists.uclibc.org/pipermail/uclibc-cvs/2005-August/019383.html
-  configureFlags = stdenv.lib.optional hostPlatform.isDarwin "--disable-nls";
+    ++ stdenv.lib.optional (hostPlatform != buildPlatform) "mr_cv_target_elf=yes"
+       # Libelf's custom NLS macros fail to determine the catalog file extension
+       # on Darwin, so disable NLS for now.
+    ++ stdenv.lib.optional hostPlatform.isDarwin "--disable-nls";
 
-  nativeBuildInputs = [ gettext ];
+  nativeBuildInputs = [ gettext ]
+       # Need to regenerate configure script with newer version in order to pass
+       # "mr_cv_target_elf=yes", but `autoreconfHook` brings in `makeWrapper`
+       # which doesn't work with the bootstrapTools bash, so can only do this
+       # for cross builds when `stdenv.shell` is a newer bash.
+    ++ stdenv.lib.optional (hostPlatform != buildPlatform) autoreconfHook;
 
   meta = {
     description = "ELF object file access library";