Update buildroot to 2021.02.5 (#1566)

Signed-off-by: Stefan Agner <stefan@agner.ch>

buildroot/package/qt5/qt5base/0009-Fix-build-on-riscv32.patch

@@ -0,0 +1,45 @@
+From 035dc537bee26e3b63a211b2835d8560439e161f Mon Sep 17 00:00:00 2001
+From: Fabrice Fontaine <fontaine.fabrice@gmail.com>
+Date: Fri, 27 Aug 2021 16:28:32 +0200
+Subject: Fix build on riscv32
+
+riscv32 fails to build because __NR_futex is not defined on this
+architecture:
+
+In file included from thread/qmutex_linux.cpp:45,
+                 from thread/qmutex.cpp:804:
+thread/qfutex_p.h: In function 'int QtLinuxFutex::_q_futex(int*, int, int, quintptr, int*, int)':
+thread/qfutex_p.h:116:30: error: '__NR_futex' was not declared in this scope; did you mean '_q_futex'?
+  116 |         int result = syscall(__NR_futex, addr, op | FUTEX_PRIVATE_FLAG, val, val2, addr2, val3);
+      |                              ^~~~~~~~~~
+      |                              _q_futex
+
+Pick-to: 6.1 6.2
+Fixes: QTBUG-96067
+Change-Id: Ib6a9bcc496f37e69ac39362cb0a021fccaf311f5
+Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
+[Retrieved from:
+https://code.qt.io/cgit/qt/qtbase.git/commit/?id=035dc537bee26e3b63a211b2835d8560439e161f]
+---
+ src/corelib/thread/qfutex_p.h | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/src/corelib/thread/qfutex_p.h b/src/corelib/thread/qfutex_p.h
+index 40482b6fc1..037207a5c0 100644
+--- a/src/corelib/thread/qfutex_p.h
++++ b/src/corelib/thread/qfutex_p.h
+@@ -103,6 +103,11 @@ QT_END_NAMESPACE
+ // if not defined in linux/futex.h
+ #  define FUTEX_PRIVATE_FLAG        128         // added in v2.6.22
+ 
++// RISC-V does not supply __NR_futex
++#  ifndef __NR_futex
++#    define __NR_futex __NR_futex_time64
++#  endif
++
+ QT_BEGIN_NAMESPACE
+ namespace QtLinuxFutex {
+     constexpr inline bool futexAvailable() { return true; }
+-- 
+cgit v1.2.1
+

buildroot/package/qt5/qt5base/qt5base.mk

@@ -277,7 +277,7 @@ QT5BASE_ARCH_CONFIG_FILE = $(@D)/mkspecs/devices/linux-buildroot-g++/arch.conf
 ifeq ($(BR2_TOOLCHAIN_HAS_LIBATOMIC),y)
 # Qt 5.8 needs atomics, which on various architectures are in -latomic
 define QT5BASE_CONFIGURE_ARCH_CONFIG
-	printf 'LIBS += -latomic\n' >$(QT5BASE_ARCH_CONFIG_FILE)
+	printf '!host_build { \n LIBS += -latomic\n }' >$(QT5BASE_ARCH_CONFIG_FILE)
 endef
 endif