lib: remove uncessary #includes from headers

Only include what the header itself needs. The big fish here is
intel-gpu-tools.h. More will follow.

One ugly thing removed here is the duplicated GEN6_TD_CTL #define, one
of which was broken.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

lib/igt_core.h

@@ -30,6 +30,8 @@
 #ifndef IGT_CORE_H
 #define IGT_CORE_H
 
+#include <stdbool.h>
+
 bool __igt_fixture(void);
 void __igt_fixture_complete(void);
 void __igt_fixture_end(void) __attribute__((noreturn));