Drop unnecessary inclusion of "config.h"

The WGL tests should not include "config.h", since we're trying to test
the use of Epoxy, not its internals.

test/headerguards.c

@@ -21,7 +21,7 @@
  * IN THE SOFTWARE.
  */
 
-#include <config.h>
+#include "config.h"
 
 #include <epoxy/gl.h>
 

test/wgl_core_and_exts.c

@@ -21,7 +21,6 @@
  * IN THE SOFTWARE.
  */
 
-#include <config.h>
 #include <stdio.h>
 
 #include "wgl_common.h"

test/wgl_per_context_funcptrs.c

@@ -35,7 +35,6 @@
  * regardless.
  */
 
-#include <config.h>
 #include <stdio.h>
 #include <assert.h>
 

test/wgl_usefontbitmaps.c

@@ -21,7 +21,6 @@
  * IN THE SOFTWARE.
  */
 
-#include <config.h>
 #include <stdio.h>
 
 #include "wgl_common.h"