xf86drmMode.h: inline -> __inline for use with gcc -std=c89 -pedantic

Unfortunately, there are some users of libdrm installed headers that like
to be built with -std=c89 -pedantic, which does not like "inline".

However, __inline works.

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
diff --git a/xf86drmMode.h b/xf86drmMode.h
index 856a6bb..2d30184 100644
--- a/xf86drmMode.h
+++ b/xf86drmMode.h
@@ -240,7 +240,7 @@
 	uint32_t *blob_ids; /* store the blob IDs */
 } drmModePropertyRes, *drmModePropertyPtr;
 
-static inline int drm_property_type_is(drmModePropertyPtr property,
+static __inline int drm_property_type_is(drmModePropertyPtr property,
 		uint32_t type)
 {
 	/* instanceof for props.. handles extended type vs original types: */