Made system header inclusion more conservative.

diff --git a/lib/glext.c b/lib/glext.c
index 84b529e..296c7f5 100644
--- a/lib/glext.c
+++ b/lib/glext.c

@@ -30,6 +30,8 @@
 
 #include "internal.h"
 
+#include <string.h>
+
 
 //************************************************************************
 //****                  GLFW internal functions                       ****

diff --git a/lib/init.c b/lib/init.c
index 05866c5..7f77ff3 100644
--- a/lib/init.c
+++ b/lib/init.c

@@ -31,6 +31,8 @@
 #define _init_c_
 #include "internal.h"
 
+#include <string.h>
+
 
 //************************************************************************
 //****                    GLFW user functions                         ****

diff --git a/lib/internal.h b/lib/internal.h
index 0b23ca6..80469dd 100644
--- a/lib/internal.h
+++ b/lib/internal.h

@@ -51,15 +51,6 @@
 #define GLFW_STICK 2
 
 
-//========================================================================
-// System independent include files
-//========================================================================
-
-#include <stdlib.h>
-#include <string.h>
-#include <stdio.h>
-
-
 //------------------------------------------------------------------------
 // Window opening hints (set by glfwOpenWindowHint)
 // A bucket of semi-random stuff bunched together for historical reasons

diff --git a/lib/window.c b/lib/window.c
index 0dc6b3b..cce7826 100644
--- a/lib/window.c
+++ b/lib/window.c

@@ -31,6 +31,7 @@
 #include "internal.h"
 
 #include <limits.h>
+#include <string.h>
 
 
 //************************************************************************

diff --git a/lib/x11/x11_fullscreen.c b/lib/x11/x11_fullscreen.c
index 93f842f..1d3a4f0 100644
--- a/lib/x11/x11_fullscreen.c
+++ b/lib/x11/x11_fullscreen.c

@@ -31,6 +31,7 @@
 #include "internal.h"
 
 #include <limits.h>
+#include <stdlib.h>
 
 
 //************************************************************************

diff --git a/lib/x11/x11_init.c b/lib/x11/x11_init.c
index d0915b7..1560396 100644
--- a/lib/x11/x11_init.c
+++ b/lib/x11/x11_init.c

@@ -30,6 +30,8 @@
 
 #include "internal.h"
 
+#include <stdio.h>
+
 
 //************************************************************************
 //****                  GLFW internal functions                       ****

diff --git a/lib/x11/x11_window.c b/lib/x11/x11_window.c
index e6cb5e8..7a12edc 100644
--- a/lib/x11/x11_window.c
+++ b/lib/x11/x11_window.c

@@ -31,6 +31,9 @@
 #include "internal.h"
 
 #include <limits.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
 
 
 /* Define GLX 1.4 FSAA tokens if not already defined */