Bump libdrm dependency to 2.4.95

96bef051 "drm-backend: add support for writeback connectors" started using DRM_MODE_CONNECTOR_WRITEBACK and DRM_CLIENT_CAP_WRITEBACK_CONNECTORS. These were introduced in libdrm 2.4.95.

According to !311 (merged) Ubunut Xenial is the only mentioned distribution that does not provide a libdrm new enough. I think that is fine to drop now, 2016 was a good while ago.

Libdrm 2.4.95 also introduced DRM_CLIENT_CAP_ASPECT_RATIO, DRM_MODE_PICTURE_ASPECT_64_27, DRM_MODE_PICTURE_ASPECT_256_135.

The fallback definitions for the above are dropped.

libweston/backend-drm/drm-internal.h

@@ -60,10 +60,6 @@
 #include "backend.h"
 #include "libweston-internal.h"
 
-#ifndef DRM_CLIENT_CAP_ASPECT_RATIO
-#define DRM_CLIENT_CAP_ASPECT_RATIO	4
-#endif
-
 #ifndef GBM_BO_USE_CURSOR
 #define GBM_BO_USE_CURSOR GBM_BO_USE_CURSOR_64X64
 #endif
@@ -114,17 +110,6 @@
 
 #define MAX_CLONED_CONNECTORS 4
 
-#ifndef DRM_MODE_PICTURE_ASPECT_64_27
-#define DRM_MODE_PICTURE_ASPECT_64_27		3
-#define  DRM_MODE_FLAG_PIC_AR_64_27 \
-			(DRM_MODE_PICTURE_ASPECT_64_27<<19)
-#endif
-#ifndef DRM_MODE_PICTURE_ASPECT_256_135
-#define DRM_MODE_PICTURE_ASPECT_256_135		4
-#define  DRM_MODE_FLAG_PIC_AR_256_135 \
-			(DRM_MODE_PICTURE_ASPECT_256_135<<19)
-#endif
-
 
 /**
  * Represents the values of an enum-type KMS property