msdk: Fix libdrm dependency detection and usage

drm_fourcc.h should be picked up via the pkgconfig include, not the
system includedir directly.

Also consolidate the libdrm usage in va and msdk.

All this allows it to be picked up consistently (via the subproject,
for example).

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7760>

subprojects/gst-plugins-bad/gst-libs/gst/va/meson.build

@@ -81,10 +81,8 @@ if host_system == 'linux'
   endif
   platform_deps += [libva_drm_dep]
 
-  libdrm_dep = dependency('libdrm', version: '>=2.4', required: get_option('drm'))
   if libdrm_dep.found()
     platform_deps += [libdrm_dep]
-    extra_args += ['-DHAVE_LIBDRM']
   endif
 
   va_sources += va_linux_sources

subprojects/gst-plugins-bad/meson.build

@@ -398,6 +398,17 @@ if x11_dep.found()
   cdata.set('HAVE_X11', 1)
 endif
 
+# Optional dep of msdk and va
+if host_system not in ['darwin', 'ios', 'android', 'windows']
+  libdrm_dep = dependency('libdrm', version : '>=2.4.50',
+    required : get_option('drm').enabled() or get_option('msdk').enabled(),
+  )
+  cdata.set('HAVE_LIBDRM', libdrm_dep.found())
+else
+  libdrm_dep = dependency('', required: false)
+endif
+
+
 #
 # Solaris and Illumos distros split a lot of networking-related code
 # into '-lsocket -lnsl'.  Anything that calls socketpair(), getifaddr(),

subprojects/gst-plugins-bad/sys/msdk/gstmsdkallocator_libva.c

@@ -32,7 +32,7 @@
 
 #include <va/va.h>
 #include <va/va_drmcommon.h>
-#include <libdrm/drm_fourcc.h>
+#include <drm_fourcc.h>
 #include <unistd.h>
 #include "gstmsdkallocator.h"
 #include "gstmsdkallocator_libva.h"

subprojects/gst-plugins-bad/sys/msdk/gstmsdkcaps.c

@@ -32,7 +32,7 @@
 #include "gstmsdkcaps.h"
 
 #ifndef _WIN32
-#include <libdrm/drm_fourcc.h>
+#include <drm_fourcc.h>
 #include <gst/video/video-info-dma.h>
 #include "gstmsdkallocator_libva.h"
 #include <gst/va/gstvavideoformat.h>

subprojects/gst-plugins-bad/sys/msdk/gstmsdkdec.c

@@ -41,7 +41,7 @@
 #include "gstmsdkcaps.h"
 
 #ifndef _WIN32
-#include <libdrm/drm_fourcc.h>
+#include <drm_fourcc.h>
 #include <gst/va/gstvaallocator.h>
 #include <gst/va/gstvavideoformat.h>
 #else

subprojects/gst-plugins-bad/sys/msdk/gstmsdkenc.c

@@ -51,7 +51,7 @@
 #include "gstmsdkcaps.h"
 
 #ifndef _WIN32
-#include <libdrm/drm_fourcc.h>
+#include <drm_fourcc.h>
 #include "gstmsdkallocator_libva.h"
 #include <gst/va/gstvaallocator.h>
 #else

subprojects/gst-plugins-bad/sys/msdk/gstmsdkvpp.c

@@ -60,7 +60,7 @@
 #include "gstmsdkallocator.h"
 
 #ifndef _WIN32
-#include <libdrm/drm_fourcc.h>
+#include <drm_fourcc.h>
 #include "gstmsdkallocator_libva.h"
 #include <gst/va/gstvaallocator.h>
 #include <gst/va/gstvavideoformat.h>

subprojects/gst-plugins-bad/sys/msdk/gstmsdkvpputil.c

@@ -30,7 +30,7 @@
 #include "gstmsdkcaps.h"
 
 #ifndef _WIN32
-#include <libdrm/drm_fourcc.h>
+#include <drm_fourcc.h>
 #include <gst/va/gstvavideoformat.h>
 #else
 #include <gst/d3d11/gstd3d11.h>

subprojects/gst-plugins-bad/sys/msdk/meson.build

@@ -184,7 +184,6 @@ if host_machine.system() == 'windows'
 else
   libdl_dep = cc.find_library('dl', required: get_option('msdk'))
   libgudev_dep = dependency('gudev-1.0', required: get_option('msdk'), allow_fallback: true)
-  libdrm_dep = dependency('libdrm', required: get_option('msdk'))
   msdk_deps = declare_dependency(dependencies: [gstva_dep, libdl_dep, libgudev_dep, libdrm_dep])
   msdk_deps_found = gstva_dep.found() and libdl_dep.found() and libgudev_dep.found() and libdrm_dep.found()
 endif