mesa: fix softpipe/non llvmpipe build

lavapipe/swrast vk hard depends on llvmpipe and does not work with
softpipe

srcpkgs/mesa/template

@@ -35,8 +35,9 @@ build_options_default="wayland"
 # especially on big endian it's all kinds of broken, and e.g. on
 # 32-bit powerpc it does not work at all, so fall back to softpipe
 case "$XBPS_TARGET_MACHINE" in
-	i686*|x86_64*|aarch64*|ppc64le*|arm*) ;;
-	*) configure_args+=" -Ddraw-use-llvm=false" ;;
+	i686*|x86_64*|aarch64*|ppc64le*|arm*|riscv64*)
+		_have_llvmpipe=yes
+		;;
 esac
 
 # Set subpackages manually to set proper rdeps in 32bit pkgs.
@@ -51,8 +52,7 @@ replaces="libGL>=10_1<19.2.5_2 libEGL>=10_1<19.2.5_2 libGLES>=10_1<19.2.5_2"
 
 # swrast always present
 _gallium_drivers=" -Dgallium-drivers=swrast"
-_vulkan_drivers=" -Dvulkan-drivers=swrast"
-subpackages+=" mesa-vulkan-lavapipe"
+_vulkan_drivers=" -Dvulkan-drivers="
 
 # amd and nvidia drivers on all platforms except where it makes no sense
 # amd implicitly enables clover opencl, also enable hwdec and virgl too
@@ -79,6 +79,12 @@ case "$XBPS_TARGET_MACHINE" in
 		;;
 esac
 
+if [ "$_have_llvmpipe" ]; then
+	subpackages+=" mesa-vulkan-lavapipe"
+	configure_args+=" -Ddraw-use-llvm=false"
+	_vulkan_drivers+=",swrast"
+fi
+
 if [ "$_have_amd" ]; then
 	# amd cards can use clover
 	_have_opencl=yes