Merge staging into closure-size

The most complex problems were from dealing with switches reverted in
the meantime (gcc5, gmp6, ncurses6).
It's likely that darwin is (still) broken nontrivially.

pkgs/servers/http/apache-httpd/2.4.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, perl, zlib, apr, aprutil, pcre
+{ stdenv, fetchurl, perl, zlib, apr, aprutil, pcre, libiconv
 , proxySupport ? true
 , sslSupport ? true, openssl
 , ldapSupport ? true, openldap
@@ -14,12 +14,12 @@ assert sslSupport -> aprutil.sslSupport && openssl != null;
 assert ldapSupport -> aprutil.ldapSupport && openldap != null;
 
 stdenv.mkDerivation rec {
-  version = "2.4.16";
+  version = "2.4.17";
   name = "apache-httpd-${version}";
 
   src = fetchurl {
     url = "mirror://apache/httpd/httpd-${version}.tar.bz2";
-    sha256 = "0hrpy6gjwma0kba7p7m61vwh82qcnkf08123lrwpg257m93hnrmc";
+    sha256 = "165p5qgwyk1dwjypgcx5vb47xadiszs3dw28n2axplw1xifh67ik";
   };
 
   # FIXME: -dev depends on -doc
@@ -28,7 +28,8 @@ stdenv.mkDerivation rec {
   buildInputs = [perl] ++
     optional sslSupport openssl ++
     optional ldapSupport openldap ++    # there is no --with-ldap flag
-    optional libxml2Support libxml2;
+    optional libxml2Support libxml2 ++
+    optional stdenv.isDarwin libiconv;
 
   patchPhase = ''
     sed -i config.layout -e "s|installbuilddir:.*|installbuilddir: $dev/share/build|"