Should fix building samba in impure environments

svn path=/nixpkgs/branches/stdenv-updates/; revision=10296

pkgs/servers/samba/default.nix

@@ -10,7 +10,8 @@ stdenv.mkDerivation rec {
 
   buildInputs = [readline pam openldap kerberos popt iniparser libunwind fam];
   configureFlags = ''--with-pam --with-smbmount --datadir=$out/share
-  --with-aio-support --with-libiconv=${stdenv.gcc.libc}'';
+  --with-aio-support ''
+  + (if stdenv.gcc ? libc then "--with-libiconv=${stdenv.gcc.libc}" else "");
 
   postUnpack = "sourceRoot=\$sourceRoot/source";
   postInstall = ''rm -rf $out/var ; ln -s /var/samba $out/var '';