package/mesa3d-headers: fix legal-info

Commit 9d874c9051cf46ef29b763ad8db0b638f3761605 forgot to update
MESA3D_HEADERS_LICENSE_FILES

Fixes:
 - http://autobuild.buildroot.org/results/d75e90863525d4abd3d83f3f947261695a2f0d65

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/mesa3d-headers/mesa3d-headers.mk

@@ -17,7 +17,7 @@ MESA3D_HEADERS_SOURCE = mesa-$(MESA3D_HEADERS_VERSION).tar.xz
 MESA3D_HEADERS_SITE = https://mesa.freedesktop.org/archive
 MESA3D_HEADERS_DL_SUBDIR = mesa3d
 MESA3D_HEADERS_LICENSE = MIT, SGI, Khronos
-MESA3D_HEADERS_LICENSE_FILES = docs/license.html
+MESA3D_HEADERS_LICENSE_FILES = docs/license.rst
 
 # Only installs header files
 MESA3D_HEADERS_INSTALL_STAGING = YES