package/sdl2: fix build with kmsdrm

package/sdl2: fix build with kmsdrm

Build with kmsdrm is broken since bump to version 2.0.14 in commit
5e0da5c40da82d90c3f6ca037170838a6689b65b. Indeed, first patch was
already applied in this version:
https://github.com/libsdl-org/SDL/commit/9354aea19834ada7ffb90d379600a242a7aa820f
but upstream made other changes that requires EGL so add an upstream
patch to fix the build failure

Moreover, run autogen.sh instead of autoreconf as it breaks the build
and is not recommended by upstream:
https://github.com/libsdl-org/SDL/pull/4214

Fixes:
 - http://autobuild.buildroot.org/results/355c7e5092e7641d8b04ecb550e2671d70720bd2

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
[Arnout: add dependency on host-autoconf]
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>