nghttp2: 1.8.0 -> 1.9.2, unify with libnghttp2, and use multiple outputs

Note: I ignored the C++ libraries, but it appears we're not currently
using them. Once we do, we'll probably want to put them in a separate
output as well (to prevent non-C++ users from depending on Boost).

pkgs/tools/networking/curl/default.nix

@@ -1,5 +1,5 @@
 { stdenv, fetchurl, pkgconfig, perl
-, http2Support ? true, libnghttp2
+, http2Support ? true, nghttp2
 , idnSupport ? false, libidn ? null
 , ldapSupport ? false, openldap ? null
 , zlibSupport ? false, zlib ? null
@@ -9,7 +9,7 @@
 , c-aresSupport ? false, c-ares ? null
 }:
 
-assert http2Support -> libnghttp2 != null;
+assert http2Support -> nghttp2 != null;
 assert idnSupport -> libidn != null;
 assert ldapSupport -> openldap != null;
 assert zlibSupport -> zlib != null;
@@ -33,7 +33,7 @@ stdenv.mkDerivation rec {
   # "-lz -lssl", which aren't necessary direct build inputs of
   # applications that use Curl.
   propagatedBuildInputs = with stdenv.lib;
-    optional http2Support libnghttp2 ++
+    optional http2Support nghttp2 ++
     optional idnSupport libidn ++
     optional ldapSupport openldap ++
     optional zlibSupport zlib ++
@@ -51,7 +51,6 @@ stdenv.mkDerivation rec {
   configureFlags = [
       "--with-ca-bundle=/etc/ssl/certs/ca-certificates.crt"
       "--disable-manual"
-      ( if http2Support then "--with-nghttp2=${libnghttp2}" else "--without-nghttp2" )
       ( if sslSupport then "--with-ssl=${openssl}" else "--without-ssl" )
       ( if scpSupport then "--with-libssh2=${libssh2}" else "--without-libssh2" )
       ( if ldapSupport then "--enable-ldap" else "--disable-ldap" )