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>
diff --git a/tests/gem_exec_nop.c b/tests/gem_exec_nop.c
index c8fff2b..2eacd12 100644
--- a/tests/gem_exec_nop.c
+++ b/tests/gem_exec_nop.c
@@ -25,6 +25,7 @@
  *
  */
 
+#include "igt.h"
 #include <unistd.h>
 #include <stdlib.h>
 #include <stdint.h>
@@ -38,10 +39,6 @@
 #include <sys/time.h>
 #include <time.h>
 #include "drm.h"
-#include "ioctl_wrappers.h"
-#include "drmtest.h"
-#include "intel_io.h"
-#include "igt_stats.h"
 
 #define LOCAL_I915_EXEC_NO_RELOC (1<<11)
 #define LOCAL_I915_EXEC_HANDLE_LUT (1<<12)