libcamera: fix implicit dependency to libdrm

libcamera is depending on libdrm in libcamera_wrapper.cpp but it was
implicitely including the header drm_fourcc.h with libcamera
file pixel_format.h

With this patch, the libcamera plugin should explicitely depends on
libdrm as it needs DRM fourcc and should not depend on multiple
inclusion from libcamera.

Add a FourCC for Motion-JPEG compressed format. This is a temporary
addition until the format gets merged in the upstream kernel.

spa/plugins/libcamera/libcamera_wrapper.cpp

@@ -39,6 +39,8 @@
 #include <sys/mman.h>
 #include <unistd.h>
 
+#include <drm_fourcc.h>
+
 #include <spa/support/log.h>
 #include <spa/param/props.h>
 #include <spa/param/video/raw.h>
@@ -63,6 +65,14 @@ using namespace controls;
 #define DEFAULT_HEIGHT			480
 #define DEFAULT_PIXEL_FMT		DRM_FORMAT_YUYV
 
+/* Compressed formats
+ *
+ * TODO: Should be removed when the format gets merged in the
+ * libdrm.*/
+#ifndef DRM_FORMAT_MJPEG
+# define DRM_FORMAT_MJPEG	fourcc_code('M', 'J', 'P', 'G') /* Motion-JPEG */
+#endif
+
 extern "C" {
 
 	static struct {

spa/plugins/libcamera/meson.build

@@ -4,9 +4,13 @@ libcamera_sources = ['libcamera.c',
                 'libcamera-source.c',
                 'libcamera_wrapper.cpp']
 
+libdrm_dep = dependency('libdrm', version : '>= 2.4.98',
+                        required : get_option('libcamera'))
+if libdrm_dep.found()
 libcameralib = shared_library('spa-libcamera',
                           libcamera_sources,
                           include_directories : [ spa_inc ],
-                          dependencies : [ libudev_dep, libcamera_dep, pthread_lib  ],
+                          dependencies : [ libudev_dep, libcamera_dep, pthread_lib, libdrm_dep  ],
                           install : true,
 		          install_dir : join_paths(spa_plugindir, 'libcamera'))
+endif