uwsgi: set UWSGICONFIG_PHPPATH to the php.dev store

uwsgi needs to run php-config to get the include path. set the
UWSGICONFIG_PHPPATH to the php-config in the php.dev store.

Patch common.h to directly include php_session.h (since it's a separate package on
nixos).

NIX_CFLAGS_LINK was removed since it doesn't seem to be used at all

https://github.com/unbit/uwsgi/blob/master/plugins/php/common.h

pkgs/servers/uwsgi/0001-no-ext-session-php_session.h-on-NixOS.patch

@@ -0,0 +1,29 @@
+From 6b9b3559d8ce59eda6c5cd6f04224cebaaa5d0ea Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?=D0=94=D0=B0=D0=BC=D1=98=D0=B0=D0=BD=20=D0=93=D0=B5=D0=BE?=
+ =?UTF-8?q?=D1=80=D0=B3=D0=B8=D0=B5=D0=B2=D1=81=D0=BA=D0=B8?=
+ <gdamjan@gmail.com>
+Date: Tue, 8 Sep 2020 17:11:39 +0200
+Subject: [PATCH] no ext/session/php_session.h on NixOS
+
+on NixOS php_session.h is in its own package, and is not installed in
+ext/session/
+---
+ plugins/php/common.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/plugins/php/common.h b/plugins/php/common.h
+index 9bf1c069..be93f519 100644
+--- a/plugins/php/common.h
++++ b/plugins/php/common.h
+@@ -10,7 +10,7 @@
+ #endif
+ #include "ext/standard/info.h"
+ 
+-#include "ext/session/php_session.h"
++#include "php_session.h"
+ 
+ #include <uwsgi.h>
+ 
+-- 
+2.28.0
+

pkgs/servers/uwsgi/default.nix

@@ -38,8 +38,12 @@ let php-embed = php.override {
                   (lib.nameValuePair "php" {
                     # usage: https://uwsgi-docs.readthedocs.io/en/latest/PHP.html#running-php-apps-with-nginx
                     path = "plugins/php";
-                    inputs = [ php-embed ] ++ php-embed.buildInputs;
-                    NIX_CFLAGS_LINK = [ "-L${libmysqlclient}/lib/mysql" ];
+                    inputs = [
+                        php-embed
+                        php-embed.extensions.session
+                        php-embed.extensions.session.dev
+                        php-embed.unwrapped.dev
+                    ] ++ php-embed.unwrapped.buildInputs;
                   })
                 ];
 
@@ -61,6 +65,8 @@ stdenv.mkDerivation rec {
     sha256 = "0256v72b7zr6ds4srpaawk1px3bp0djdwm239w3wrxpw7dzk1gjn";
   };
 
+  patches = [ ./0001-no-ext-session-php_session.h-on-NixOS.patch ];
+
   nativeBuildInputs = [ python3 pkgconfig ];
 
   buildInputs =  [ jansson pcre ]
@@ -94,8 +100,6 @@ stdenv.mkDerivation rec {
     ${lib.concatMapStringsSep "\n" (x: x.install or "") needed}
   '';
 
-  NIX_CFLAGS_LINK = toString (lib.optional withSystemd "-lsystemd" ++ lib.concatMap (x: x.NIX_CFLAGS_LINK or []) needed);
-
   meta = with stdenv.lib; {
     homepage = "https://uwsgi-docs.readthedocs.org/en/latest/";
     description = "A fast, self-healing and developer/sysadmin-friendly application container server coded in pure C";