drm: add extern C guard for the UAPI headers

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>

include/uapi/drm/drm.h

@@ -65,6 +65,10 @@ typedef unsigned long drm_handle_t;
 
 #endif
 
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 #define DRM_NAME	"drm"	  /**< Name in kernel, /dev, and /proc */
 #define DRM_MIN_ORDER	5	  /**< At least 2^5 bytes = 32 bytes */
 #define DRM_MAX_ORDER	22	  /**< Up to 2^22 bytes = 4MB */
@@ -691,8 +695,16 @@ struct drm_prime_handle {
 	__s32 fd;
 };
 
+#if defined(__cplusplus)
+}
+#endif
+
 #include "drm_mode.h"
 
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
 #define DRM_IOCTL_BASE			'd'
 #define DRM_IO(nr)			_IO(DRM_IOCTL_BASE,nr)
 #define DRM_IOR(nr,type)		_IOR(DRM_IOCTL_BASE,nr,type)
@@ -886,4 +898,8 @@ typedef struct drm_scatter_gather drm_scatter_gather_t;
 typedef struct drm_set_version drm_set_version_t;
 #endif
 
+#if defined(__cplusplus)
+}
+#endif
+
 #endif