mesa: update to 20.1.8, add aarch64 patch

This workaround fixes xrender issues (corrupt rendering) with
Radeon cards on some boards.

Closes https://github.com/void-linux/void-packages/pull/24951

srcpkgs/mesa/patches/0001-radeonsi-On-Aarch64-force-persistent-buffers-to-GTT.patch

@@ -0,0 +1,38 @@
+From d72aa8ae74ffb7329003f9f23ffa05833af951ab Mon Sep 17 00:00:00 2001
+From: Jon Nettleton <jon@solid-run.com>
+Date: Fri, 14 Aug 2020 13:36:08 +0200
+Subject: [PATCH] radeonsi: On Aarch64 force persistent buffers to GTT
+
+This fixes a glamore corruption issue on the HoneyComb and by
+internet reports should also fix problems seen on Huaweii
+Kunpeng hardware.
+
+The root cause of the corruption needs to be worked out, but
+this patch also adds a noticable performance improvement. The
+aquarium webgl demo under chromium increases from 39-49 FPS
+when 5000 fish being rendered is selected.  Glmark scores also
+improve by ~200 with no specific tests showing any regression.
+
+Signed-off-by: Jon Nettleton <jon@solid-run.com>
+---
+ src/gallium/drivers/radeonsi/si_buffer.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/src/gallium/drivers/radeonsi/si_buffer.c b/src/gallium/drivers/radeonsi/si_buffer.c
+index 6b58aebee2d..c9e983367a0 100644
+--- src/gallium/drivers/radeonsi/si_buffer.c
++++ src/gallium/drivers/radeonsi/si_buffer.c
+@@ -151,6 +151,11 @@ void si_init_resource_fields(struct si_screen *sscreen, struct si_resource *res,
+        */
+       if (!sscreen->info.kernel_flushes_hdp_before_ib || !sscreen->info.is_amdgpu)
+          res->domains = RADEON_DOMAIN_GTT;
++
++#if defined(PIPE_ARCH_AARCH64)
++      if (size <= 1024 * 512)
++         res->domains = RADEON_DOMAIN_GTT;
++#endif
+    }
+ 
+    /* Tiled textures are unmappable. Always put them in VRAM. */
+-- 
+2.26.2

srcpkgs/mesa/template

@@ -1,6 +1,6 @@
 # Template file for 'mesa'
 pkgname=mesa
-version=20.1.7
+version=20.1.8
 revision=1
 wrksrc="mesa-${version}"
 build_style=meson
@@ -23,7 +23,7 @@ license="MIT, LGPL-2.1-or-later"
 homepage="https://www.mesa3d.org/"
 changelog="https://docs.mesa3d.org/relnotes/${version}.html"
 distfiles="https://mesa.freedesktop.org/archive/mesa-${version}.tar.xz"
-checksum=4de9dd0cb2ca367606cada421db62fbf6d276dfd533e522bfab6001ff9aba288
+checksum=df21351494f7caaec5a3ccc16f14f15512e98d2ecde178bba1d134edc899b961
 
 build_options="wayland"
 build_options_default="wayland"