Re-order includes for "_POSIX_C_SOURCE"

One FreeBSD, the build was getting errors about _POSIX_C_SOURCE
being redefined. The fix for this is to make sure that Python.h
gets included before any system libraries.

kitty/child-monitor.c

@@ -5,8 +5,8 @@
  * Distributed under terms of the GPL3 license.
  */
 
-#include "threading.h"
 #include "state.h"
+#include "threading.h"
 #include "screen.h"
 #include "fonts.h"
 #include <termios.h>

kitty/data-types.h

@@ -7,13 +7,12 @@
 
 #pragma once
 
-
+#define PY_SSIZE_T_CLEAN
+#include <Python.h>
 #include <stdint.h>
 #include <stdbool.h>
 #include <poll.h>
 #include <pthread.h>
-#define PY_SSIZE_T_CLEAN
-#include <Python.h>
 // Required minimum OpenGL version
 #define OPENGL_REQUIRED_VERSION_MAJOR 3
 #define OPENGL_REQUIRED_VERSION_MINOR 3

kitty/glfw-wrapper.c

@@ -1,7 +1,7 @@
 
-#include <dlfcn.h>
 #include "data-types.h"
 #include "glfw-wrapper.h"
+#include <dlfcn.h>
 
 static void* handle = NULL;
 

kitty/keys.c

@@ -5,8 +5,8 @@
  * Distributed under terms of the GPL3 license.
  */
 
-#include "keys.h"
 #include "state.h"
+#include "keys.h"
 #include "screen.h"
 #include "glfw-wrapper.h"
 #include "control-codes.h"

kitty/shaders.c

@@ -5,8 +5,8 @@
  * Distributed under terms of the GPL3 license.
  */
 
-#include "gl.h"
 #include "fonts.h"
+#include "gl.h"
 
 enum { CELL_PROGRAM, CELL_BG_PROGRAM, CELL_SPECIAL_PROGRAM, CELL_FG_PROGRAM, CURSOR_PROGRAM, BORDERS_PROGRAM, GRAPHICS_PROGRAM, GRAPHICS_PREMULT_PROGRAM, BLIT_PROGRAM, NUM_PROGRAMS };
 enum { SPRITE_MAP_UNIT, GRAPHICS_UNIT, BLIT_UNIT };