lib: add a single include header

Add a header that includes all the headers for the library. This allows
reorganisation of the library without affecting programs using it and
also simplifies the headers that need to be included to use the library.

Signed-off-by: Thomas Wood <thomas.wood@intel.com>

tests/gem_tiled_pread_pwrite.c

@@ -44,6 +44,7 @@
  * Note that this test will use swap in an effort to test all of ram.
  */
 
+#include "igt.h"
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
@@ -56,10 +57,6 @@
 
 #include <drm.h>
 
-#include "ioctl_wrappers.h"
-#include "drmtest.h"
-#include "intel_io.h"
-#include "igt_aux.h"
 
 IGT_TEST_DESCRIPTION("Test swizzling by testing pwrite does the inverse of"
 		     " pread.");