Use HOST_QEMU_OPTS instead of patching Buildroot

buildroot_patches/README.md

@@ -1,5 +1,7 @@
 # Buildroot patches
 
+Every `.patch` file in this directory gets applied to build-root before anything else is done.
+
 Ideally, this directory should be empty, and we should use only built-in Buildroot configuration mechanisms.
 
 But alas, life is sometimes not ideal.

buildroot_patches/qemu_sdl.patch

@@ -1,14 +0,0 @@
-https://bugs.busybox.net/show_bug.cgi?id=9936
-
-diff --git a/package/qemu/qemu.mk b/package/qemu/qemu.mk
-index 66efcba..1e09ea4 100644
---- a/package/qemu/qemu.mk
-+++ b/package/qemu/qemu.mk
-@@ -74,6 +74,7 @@ HOST_QEMU_SYS_ARCH ?= $(HOST_QEMU_ARCH)
- 
- ifeq ($(BR2_PACKAGE_HOST_QEMU_SYSTEM_MODE),y)
- HOST_QEMU_TARGETS += $(HOST_QEMU_SYS_ARCH)-softmmu
-+HOST_QEMU_OPTS += --enable-sdl --with-sdlabi=2.0
- HOST_QEMU_OPTS += --enable-system --enable-fdt
- HOST_QEMU_DEPENDENCIES += host-dtc
- else

run

@@ -19,15 +19,21 @@ case "$arch" in
     defconfig=qemu_arm_versatile_defconfig
     ;;
 esac
-for p in ../buildroot_patches/*.patch; do
-    patch -N -r - -p 1 <"../buildroot_patches/${p}" || :
+for p in "$(find '../buildroot_patches/' -maxdepth 1 -name '*.patch' -print)"; do
+    patch -N -r - -p 1 <"$p" || :
 done
 make BR2_EXTERNAL="$(pwd)/../kernel_module" "$defconfig"
 # TODO Can't get rid of this for now.
 # http://stackoverflow.com/questions/44078245/is-it-possible-to-use-config-fragments-with-buildroots-config
 cat ../buildroot_config_fragment >> .config
-# TODO there is no make host_qemu-rebuild ?
-rm -f output/build/host-qemu-2.7.0/.stamp_built
-env -u LD_LIBRARY_PATH make BR2_JLEVEL="$(($(nproc) - 2))" kernel_module-rebuild all
+env \
+  -u LD_LIBRARY_PATH \
+  make \
+  BR2_JLEVEL="$(($(nproc) - 2))" \
+  HOST_QEMU_OPTS="--enable-sdl --with-sdlabi=2.0" \
+  host-qemu-rebuild \
+  kernel_module-rebuild \
+  all \
+;
 cd ..
 ./runqemu "$@"