package/libdrm: add license file

Add xf86drm.c as the license file and while at it, update the indentation
in hash file (two spaces)

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/libdrm/libdrm.hash

@@ -1,3 +1,6 @@
 # From https://lists.freedesktop.org/archives/dri-devel/2020-November/285471.html
-sha256 3fe0affdba6460166a7323290c18cf68e9b59edcb520722826cb244e9cb50222  libdrm-2.4.103.tar.xz
-sha512 15b098b962008271400692b6b15ecb7e22676f8698e0220ad969735ac2315ccc737d19558afb6abda82bae15117e5f306c048184a2369f434b85ecaa670ca885  libdrm-2.4.103.tar.xz
+sha256  3fe0affdba6460166a7323290c18cf68e9b59edcb520722826cb244e9cb50222  libdrm-2.4.103.tar.xz
+sha512  15b098b962008271400692b6b15ecb7e22676f8698e0220ad969735ac2315ccc737d19558afb6abda82bae15117e5f306c048184a2369f434b85ecaa670ca885  libdrm-2.4.103.tar.xz
+
+# Hash for license file
+sha256  2ece103921b7b5619198b9572fb9242db7bbfa6d3b33f9f93f22e1fb738ed8ac  xf86drm.c

package/libdrm/libdrm.mk

@@ -8,6 +8,7 @@ LIBDRM_VERSION = 2.4.103
 LIBDRM_SOURCE = libdrm-$(LIBDRM_VERSION).tar.xz
 LIBDRM_SITE = https://dri.freedesktop.org/libdrm
 LIBDRM_LICENSE = MIT
+LIBDRM_LICENSE_FILES = xf86drm.c
 LIBDRM_INSTALL_STAGING = YES
 
 LIBDRM_DEPENDENCIES = \